With Supernatural and Buffy crossover if Xander is a lost realtive its usually as John Winchester son or Bobby Singer nephew so this is something different.

Namely Xander as a close relative of Computer Genius/Hunter Ash who despite being a alcoholic? is very close, supportive, accepting and protective of Xander and flips his lid and rescues him when he finds out that Xander

- been fighting the supernatural since he was 13/14

- was sent to hell during the acathla incident [for no more than 30 years before being sent or brought back] OR Xander being forced to kill his willingly possessed step-dad in self defence and then being shunned for it by the Gang.

after being sent all of Xander personal possessions which includes Xander very detailed hunter journal, a devil trap poster for the ceiling, SPN database secretly created from Giles library and the detailed locations of all of Sunnydale caches-secrets.

Must haves

- Ash saving Xander when he was young from either being sold to demons or sacrified by demons worshippers

- Xander getting his own warding tattoo's after a full cleansing and medical

- Willow, Oz and Giles getting out-geniused by a kickass Ash before leaving town with Xander & a greatly enhanced bank account thanks to the town newly emptied caches

- Xander having dealt with Supernatural style demons as well as Buffy verse whilst in Sunnydale possibly without the gang knowledge.

- Xander later becoming very close to the winchester sons, as a lover, best friend, or adoptive brother

- Xander positively changing things in the supernatural universe = maybe taking out Meg before Chicago, safely destroying the devil gate keyhole, saving Ash and the Roadhouse patrons....etc

- Xander as a Psychic = Empath, Medium, Telekinetic or Clairvoyant

Alternatively you could have him as a close relative of Caleb instead afterall they are both weapons nuts.

Xander as either the hidden son of Tony Stark from around mid-late teens to early twenties OR the adopted son of Tony Stark

Xander runs away from home as a teenager{14-17(due to abuse, backstabbing, injury...all of the above...)} and runs into Tony, ends up saving his life, which eventually leads to them finding out the family connection.

Tony and his half brother Nathan join together to help and get to know Xander, ensuring he gets extensive, effective & excellent Healing, Therapy, Tutoring and Self Defence Training{in case of kidnapping & bullying}

Slowly they each form a strong and solid accepting/protective/loyal/resiliant/ perceptive/supportive/healing/in-depth relationship with each other - in the case of Tony and Nathan it also means healing at least some of the old personal hurts/issues with themselves and each other 

No one outside of the Starks and JARVIS know of the family relationship or who Xander was previously, and they try and keep it that way even after the death of Stane.

All three are skilled BAMFs, Engineers, Business Men, Humanitarians, Façade Wearers, Secret Finders & Keepers{includes the Supernatural world}, Fighters, Linguists, People Readers...

Just imagine Fury and everyone else reactions to the fact there are more Starks out there.

Xander as a experienced former full time hunter & part time Construction worker/college student out in LA after high school graduation and realizing that the other Scooby gang weren't really his friends. Ends up falling in love & secretly marrying Lindsey McDonald which unknowingly changes things in the Angel verse for the better, however Lindsey still dies several years later.

= Ends up meeting Eliot Spencer and the team a year later, after an initial freak out at seeing Eliot, ends up slowly becoming a valued part of the overprotective family, particularly by Eliot & Nate {explosive & weird crap expert, backup hitter maybe}

= Bonus points if Xander and Lindsey had two sons together before Lindsey died

= Double bonus points if Lindsey manages to up Xander confidence levels enough to believe in himself & his own talents beyond Hunting & Construction such as Music or Painting...etc

Challenge – Alex Kent formaly Xander Harris 

• Set during high school for both of them though Alex can be older or younger than Clark

• Both Alex and Clark work through their issues through various mediums = art, music, stories, carpentry, mechanics, cooking...

• Alex is a metahuman with a heightened healing factor, the gifts of Empathy and a more active power such as Force Fields...etc {though nothing that would make everything simple like Telepathy} – Clark also discovers his abilities quite quickly once they meet due to an accident

• Deeply mourning the deaths of best friend Jesse who was like a brother and his secret military brat Boyfriend aka first love = both of whom were the only ones who previously knew of his metahuman abilities

• The Harris's are killed in a fire {doesn't really mourn them, instead mourns for what should/could of been if there was no abuse, neglect, indifference, alcoholism..etc} = does inherit a reasonable amount of money from insurance once the debts...etc are paid

• Alex belongings reduced afterwards to Boyfriend Ninja Motorcycle, Jesse Guitar & a chockablock duffle bag with his clothes, Jesse-Boyfriend Jewelry, Essentials, CD storage books, personal folder{his true Ids-records-paperwork-licences...}, His-Jesse-Boyfriend Journals{packed with art-lyrics-keepsakes-photographs...}, hunter journal, blessed weapons, first aid kit, supplies, odds & ends...etc

• Alex having had experience & previously earning money in the darker aspects of the world – fight clubs, stealing, drag racing, hustling pool-darts-cards, stripping...etc making him much more likely to spot various human threats early as well as call anyone and everyone on their BS or unwarranted hurting/pushing of Clark

• Manages to make his way to Smallville after the Harris's deaths where he's adopted by his aunt and uncle {the Kents} which leads to a new surname, nickname, paperwork, licences, accounts, practical wardrobe, calmer personality{no more joker-slacker facade}, full medical, full education testing, gifting Kents with half of his parents insurance settlement so less money problems for them

• Or alternatively Alex meets Kal whilst living in metropolis, becomes confidants and helps him out - so much so that Clark calls him once he's back to himself and Alex moves to Smallville to be closer to him to help with his issues - afterwards Martha recognises him as her nephew and it then leads to the new Surname, nickname, paperwork...etc

• Alex & Clark bonding very closely as brothers with unconditional and beneficial support, brotherly love, trust, friendship, acceptance, truth, clarity, lack of secrets...{outside of their powers possible secrets could be taking college classes, being stolen at birth or lab created{Alex}, teenage pregnancy...}

• Both of them end up forming a good solid relationship with Lex Luthor despite everyone else's protests which leads to one of them initially dating him and the other dating Bruce Wayne or Oliver Queen as Lex doesn't go crazy or evil though he does still die

• Clark gets over his Lana crush much quicker as he realizes that it all based on fantasy and not reality as well as lets Chloe down gently about her crush

Xander was at some point during High School made into a whitelighter ordered to safeguard the Hellmouth with a thorough grounding in everything he needs to know thanks to a necessary mental download which gets translated into his own comprehensive key locked journal providing the full in-depth lowdown of the Supernatural/Magical/Paranormal Good, Bad & Neutral

Possible charges include the Scooby Gang who he's becoming increasingly disallusioned with, Amy, Wells Brothers, Michael, Jonathan, Tara, Faith... very few of which actually find out he's a whitelighter{not Buffy/Dawn/Willow}, however despite that still manages to effect great positive changes which sidestep later issues

 Eventually Xander falls in love with & marries Chris Halliwell

Xander Winchester

Xander as a half brother or twin

1. Gets adopted by Hunter Caleb whilst age 15/16 & post Acathla or Graduation after meeting during some Sunnydale Cache raiding – Caleb helps him get a better grounding in self defence, supernatural, weapons, first aid... as well as heal from his family & friends abuse & neglect until he finds Caleb body and his Birth dad on the phone.

2. The Gang shunning him after he's forced to kill his possessed step-dad in self defence since despite being possessed he was still human & with a soul – afterwards his big brother Dean comes into town as his emergency contact whilst the gang expect Xander to crawl back to them begging for forgiveness, finds out everything that's happened, thoroughly kicks the Scooby gangs asses and then takes his brother under his wing without John knowledge whilst Sam is at Stanford{side affect could be they stopped in to see Sam & secretly de-possess his friend and put up full protections}

3. Xander bailing on the Gang after realizing at the very least how much they take advantage of him and ends up hunting alone across America until he meets the rest of his family one of three ways 1) at shotgun point in the middle of a hunt, 2) singing & playing guitar on the street, or 3) hitchhiking – side note could be Xander meeting Faith whilst on the Road and once realizing where she's going and the reason why gives a thorough heads up on sunnydale & the gang

4. Xander de-aged by willow to become more of a yes man, gets sent to his unknown to the gang, brother Sam, whilst he's at Stanford and is eventually cured by brotherly love/acceptance, Bobby or Pastor Jim

5. Teen Xander being forced to take care of his suicidal and alcohol addicted [already has issues thanks to the Harris's] half brother Sam after Dean Deal comes due whilst also struggling with keeping Ruby away from them and dealing with a sudden diagnosis of cancer

6. The hospital calling Sam at Stanford saying Xander in a bad way and Sam learning what it truly means to be the big brother whilst Xander heals = could be due to cancer, suicide attempt, returning from hell, bad hunt...etc

7. Xander as Sam twin that was stolen at birth and reunited age 16 after he'd been hunting for two years on the hellmouth & the Acathla incident – ends up going to Stanford with Sam to protect him whilst secretly keeping up with the protections, hunting on the side, working part time in a gunshop, keeping in touch with Dean & Bobby, De-possessing Brady, finding a hunter boyfriend...etc

8. Xander getting legal guardianship of half brother Adam after his mom dies and together with Xander boyfriend whose another trained hunter & Jack O'Neill clone sets out to help stop the Apocalypse whilst working out of their own home base that has enough rooms/beds for them, Dean, Sam, John, & their uncle Clay{loosers}

In each bunny the brothers each have a ring that is warded against being taken off, unwilling teleportation, physical & spiritual possessions, harmful/malicious & shoddy magicks, tracking, impersonation, mental & emotional compulsion/influence & tampering, unwilling magical & psionic bonds...

Bunny [Set any time up to Joyce dying]

Sheriff Carter finding out that he is Xander father

[with Carter and Eureka possibly also being a Wizarding community like in Oh no
he didn't by josette grover]

Must Have's
1) Joyce written as being a good but flawed woman not a idol of virtue & Dawn
going into a estranged relatives care upon death eg Aaron Hotchner
2) Nathan somehow successfully shutting down or shielding the hellmouth, maybe even having the town/council/initiative shut down or rebuilt
3) ALL of the scooby's and their allies having reality & the possibilities of
real life consequences for their actions and inactions pointed out to them
4) Willow not being the smartest one in the room just academic smart next to
Sunnydale sheep standards
5) Xander being fearful of Willow learning magic considering her personality &
taking steps eg protection tattoo's....

Possible multiple secrets for Xander to have: -
= Working various jobs since he was a young child

= Studying online/night school for his GED, Degree, various certificates as well
as self defence and EMT classes
= Having a secret supportive male lover at college or outside town
= Large locked saving account outside town from years of bad guy
looting/scavenging,
= Currently or previously squatted in Jesse old home living out of a dufflebag
after being disowned for standing up to his family whilst hyena possessed
= Single father to a son due to the Initiative or hyena possession
= Long term health issues due to abuse, fish taint, chumash curse, willow
magical blasts...etc
= Being a skilled empath, shaman and/or medium
= Has him collecting extensive, evidence backed up, full records on the team,
allies, local practitioners, underground population, Initiative, council and
Sunnydale as personal insurance with multiple copies in various safe places
(Corrupt, Negligent, Incompetent, Stagnant, Criminal, Unstable...etc)
= Having extensive trust issues with all the team members and allies not just
willow and buffy
= Suffering from PTSD

Any Takers :)

Either Pre-Series or Post Master

The whole town is thoroughly investigated by ALL relevant governement agencies which leads to a mayor death whilst resisting arrest and a full rebuilding - No more corruption, negligence, stagnancy, incompetence...etc with Key posts such as teachers, cops, doctors, therapists, managers, magic shop owner...etc being filled in by good, experienced, no BS, practical, realistic, insightful, strategic, responsible, modern and proactive: hunters, psychics, natural born witches, halfies, whitelighters...etc

The whole town is 1) thoroughly blessed and cleansed of at least 50+ years of bad energies, with the Hellmouth drained down to half strength and warded against leaking and opening, 2) cleaned out of abandoned, dangerous and hidden supernatural, magical and paranormal caches, 3) cleared of at least 60% of its vampire population

All Citizens fully cleansed of all the hellmouth corruptive taint, bonds & influence maybe through the water system which would further help in getting rid of the bad guys... 

All Kids – Forced to attend an accelerated Summer School to get up to State Education Standards for their year groups as well as good group and individual therapy {catches trouble cases before they can become threats such as Warren, Tucker, Marcy, Jonathan, Amy and her Mom, Willow...}

Willow – Sent to a good foster care family and community service for her Hacking after a stint in Juvie whilst her parents are discredited & arrested for child neglect, endangerment, abandonment...

Xander – Gets Adopted by the McNally's whilst his family is arrested for fraud, DUI, child abuse, neglect, endangerment...

Xander Rings: warded against being taken off, unwilling teleportation, physical & spiritual possessions, harmful/malicious & shoddy magicks, tracking, impersonation, mental & emotional compulsion/influence & tampering, unwilling magical & psionic bonds...

How would Giles and Buffy react to all the positive changes?, would the scooby gang still form?, would they shun the others in true council fashion?, will they actively work against the others?...

How would Xander, Jesse and Willow react to the positive changes?, would willow, xander and Jesse still be friends after everything?, will willow end up bitter about everything as she's not top academic dog anymore?...

How would Angel react to all the positive changes?, would someone be able to negate or fix his curse as well as give him a continuous reality check?...

What if Xander had a down to earth hands on Grandpa that he often stayed with who was a former Marine & FBI Agent that had escaped from his old Watcher family, who gave him a thorough grounding in magic, supernatural, demonic, paranormal, hunting, law, self defence, tactics, weapons, wilderness survival-tracking, money, people reading, problem solving, forensics, languages, medic, investigating, field psychology, carpentry, mechanics, handyman, security...etc

Helped ensure his grandson not only survived but thrived in both worlds with practical life skills, particularly when he realized that Xander is the first in a completely new magical bloodline like melinda warren was = also helped him secure proper accurate records outside Sunnydale, the Harris & Willow Interferences under legal birth name{education(distant learning), medical, legal, financial, employment, personal...}

How would all this change Xander for the better, particularly with Grandpa not liking Willow and therefore not allowing her, or anyone else, to influence his Grandson unduly in any shape or form so that Xander can form his ownself & opinions

Xander being related to four+ overprotective snarky no BS people who once they find out how much he's been screwed over {by his parents, willow & her hacking/magic, rosenburgs & their biased psychology, snyder manipulations & sunnydale outdated-corrupt-neglegent-incompetent system...etc} set out to help him every way they can whilst also thoroughly kicking ass with regards to at the very least the Harris's, Buffy, Giles, Willow, Cordelia, Oz, Joyce, Snyder... if not the whole of sunnydale messed up system, with positive lasting results, even if the results are only in Xander, the Family and the innocents best interests.

Possible Relatives = Nathan Stark, Jack O'Neill, Gregory House, Tim Speedle, Tony Dinozzo, Aaron Hotchner or David Rossi, Ray Kolwalski, Nathan Ford, Steve McGarrett Or Danny Williams...

After reading  The Pen is a Sword: The Blood Books on AO3 by A_Being_Of_Violet_Fire not long after reading several Eureka fics this came up

= Harry & Percy forming a solid friendship and eventual relationship behind everyone backs, as the overlooked ones, that leads to them fully escaping wizarding europe, after draining the Potter/Black vaults/properties of everything valuable, for the Magical/Supernatural/Intellectual sanctuary of Eureka

Both gain full asylum/citizenship, new Identities, tailored in-depth magical & mundane education, medical & healing, weekly therapy{not Barlow}, purification ritual, their secret dream jobs{opposite expectations}, true friend/brother/dad in Nathan Stark, birthrights, makeovers...

Eventually they have three sons together{mpreg or surrogates or adoption} that don't get subjected to the Dursley or Weasley version of parenting{abuse, overbearing, neglect or comparing kids}

Harry ends up forming a solid friendship with Jack Carter when he arrives in town, helping him adjust, stay sane & keep his secrets - Keeps him sane after Percy dies the year before

Main Crossovers = Buffy, Charmed, Supernatural

What If Xander had a brother who died before Jesse & Xander reacted by extensive training so he could protect himself, his platonic soul mate Jesse & his emotionally stunted step sister Willow – however after Jesse death he moves from defence to offense and starts nightly hunts & mapping out the various lairs, nests, caches, deaths...etc so he can regularly hit the hot spots

Leads to major conflict with the overbearing & willfully blind special syndrome gang = Willow{conflicts with her fantasy version of Xander}, Buffy{wants to subject her version of normal on him} and Giles{impractical snobby researcher & council lackey}

Training = Supernatural, Self Defence, Demonic, Tracking, Weapons, Paranormal, Strategy, First Aid, Thieving, Magical...

Bonus Points if Xander is a part of an old & unique natural born witch family that has hunted ALL styles of demonic/supernatural/paranormal/magical threats, something which is reflected in their comprehensive book of shadows = leads to him having Leo as his Whitelighter/Mentor, a supportive power{empathy or Sensing evil} & a highly destructive active power{energy blasts-pyrokinesis-molecular combustion-energy waves-advance telekinesis-energy balls-molecular dispersion...}

Bonus Bonus Points if Xander is shown as highly practical, knowledgeable, competent, proactive, realistic, perceptive, blunt, driven, strategic...

Triple Bonus Points if Xander has protective tattoos against all types of possessions, non healing magic, psychic manipulation & impersonations{skinwalkers-shapeshifters..}

Challenge

= Xander is de-aged & possibly sent across realms to become the son of BAMF teen Stiles Stilinski and maybe a stalker/roofies 

= Stiles has secretly been training in self defence, weapons, magic, first aid, investigation techniques, profiling, hacking & the supernatural thanks to what been happening as he doesn't want to be a victim. 

= After getting custody of baby Xander takes a hard look at his life, friends, allies, himself and his priorities

= Ends up being less inclinded to help/lie/backup bad friend Scott & the Hale Pack unless truly necessary.

= Becomes very anti Argent family

= Doesn't tolerate anyone BS &/or Manipulations in any shape or form against him, his dad or innocents

What if Xander dressed up as youngish Charles Xavier for Halloween instead of a Soldier and he kept not only the very useful memories but the gift of Telepathy as well? Particularly if Xander thanks to the way he's grown up unconciously & constantly scans those around him for threats - hearing & finding out things he shouldn't > leading Xander to proactively taking care of various threats in sunnydale much more quietly, efficiently and effectively including the teams various attitudes as well as providing some necessary perspective for Xander with regards to his life and himself

Possibile Crossovers

1) {CHARMED} Xander finds out that he's a Natural Born Witch with Halloween just breaking through the binding, that was placed by the Elders due to his parents continuous addictions, and possibly adding another active power = gets the support/help of the Elders/whitelighters as he learns of his heritage, controls his gifts and handles sunnydale/gang > later on could move to San Francisco and form an alliance with the Charmed ones and some others in keeping San Fran safe and each other grounded in reality

1.5) Xander as just a natural Telepath, though thanks to where he was born and how he got/activated his powers still gains Elders/whitelighters support as he learns to control his gifts and handle sunnydale/the gang = later on he could also be the one to help support Leo supporting the Charmed ones and getting their heads out of their asses as needed

Added bonus if Xander and Paige become best friends, helping each other heal and supporting each other against unreasonable sisters/friends that have constant trouble accepting them as they are and not zeppo/replacement instead of friend/sister.

2) {SUPERNATURAL} Xander as one of Azazel children with his gifts coming out sooner thanks to Halloween - leads to him heading several things off

3) {SENTINAL with further possible crossovers in SGC or CSI if sentinals/guides are known} Xander as a powerful guide qualities become more telepathic in nature

4) {X-Men Evolution Or X Men The Movies} Xander as the Psychic son of the real Charles Xavier who with his own Telepathy senses that something has happened, investigates it, fixes it and then fosters/adopts Xander.

Must Not Have:- Xander telepathically powerful enough to read more than a small city

The Buffy Verse where Xander was Born with the gift of Power Immunity -  User is immune to all or certain supernatural powers and effects, although indirect attacks can still effect the user

• Ability Resilience - Immune to superpower manipulation-based attacks.

• Elemental Immunity - Immune to element-based attacks and abilities.

• Evil Immunity - Immune to becoming or to anything that's pure evil.

• Fate Immunity - Immune to the forces of Causality and Fate

• Illusion Awareness - See through illusions.

• Life Resilience - Immune to Death Manipulation.

• Magic Immunity - Immune to magic.

• Panmnesia - Immune to memory manipulating abilities.

• Paranormal Immunity - Immune to paranormal-based attacks, abilities and effects.

• Precognitive Immunity - Can't be seen in precognitive-based abilities.

• Psychic Shield - Immune to telepathic, empathic and mental abilities.

• Reality Anchoring - Immune to reality manipulation-based abilities.

• Seduction Immunity - Immune to seductive love, lust and sex-based abilities.

• Semi-Immortality - Immune to aging-based abilities.

• Shapeshifting Awareness - See through a shapeshifters disguise.

• Soul Anchoring - Immune to Soul-affecting powers.

• Temporal Protection - Immune to alterations of the timeline changing.

• Temporal Immunity - Immune to temporal-based powers

• How much different would everything be? Would Xander still be as close to Willow if he wasn't as effected by the Hellmouth and didn't constantly forget/ignore the deaths & various strangness? How would Willow react when every spell she decides to cast on her Xander toy failed? What if it allowed him to save a would have been forgotten little brother, that he loved & protected unconditionly, by allowing him to see past Illusions/shapeshifting abilities...etc of his would be killer?