i made a tier list outlining sonic the hedgehog's expansive and incredibly complicated found family as it appears in the hit smash bros-based d&d 5e campaign Bash Extravaganza. yes, i said tier list, not tree. there is no other way i could have feasibly formatted it. list itself + explanation of certain categories under the cut. click on it for quality.
tails: "our meeting is a fulfillment of a cosmic truth and the idea of a world without you is so strange and unnatural that it simply does not occur to me. i am your brother before i am anyone else's brother, son, cousin, or nephew. if i did not have any of these people i would still have you and if i had all of them except for you my life would not feel complete." distinct from sibling tier because none of his siblings are his siblings in the way that tails is
[family] by relation: he shares a familial relationship with them through someone else (adopted by the same person on separate occasions, for example) and does consider them family, but probably wouldn't consider them family if not for the shared relationship. this is the "yeah sure" category
[family] by choice: he considers them family, and would consider them as such with or without a previously existing shared relationship. people in "by relation" can move into "by choice" if sonic is close enough to them, or in other words if "yeah sure" becomes "100% absolutely"
nebulous unlabeled family: they don't really go in any particular category but if asked if he considers them family he'd go "uhhhhh y'know? yeah" and not elaborate.
[family] adjacent friend: he doesn't call them [family] nor does he consider them as such, but he behaves around them in a manner similar to how he behaves around his actual [family]. sibling-adjacent friend could probably fit more sonic characters like silver in there but i didn't feel like it
family of family: what it says on the tin. he shares a familial relationship with them thru someone else but does not consider them family either because they just aren't that close, had a falling out, or literally have not met. eternally incomplete tier because all four of his parents are serial adopters and every now and then he gets a text like "hey you have a new sibling"
honorable mentions: im not sure if he considers them family but while i was making the list his muse picked them up and rotated them for a bit and then set them back down without giving me a conclusive answer one way or the other.
bronev: on the list for the express purpose of emphasizing how not on the list he is. fuck this guy.
note 1: making the distinction between By Choice and By Relation is important because there are situations like, for example, the fact that he is cousins with both Joker (Persona 5) and Goro Akechi. Joker and Akechi aren't cousins with each other and are, in fact, dating. Akechi is Sonic's cousin because Sonic's uncle (Jean Descole) adopted him, but Joker is Sonic's cousin because they looked at each other and went "yeah we're cousins now." but, again, they aren't each other's cousins. they both just happen to be cousins with sonic.
(akechi is in By Choice now, but he was in By Relation in previous editions of the list. he moved into Choice as they grew closer)
note 2: the picture of the house sparrow in Cousins (By Relation) isn't representative of an actual sparrow. it's a character named Sparrow (who is an oc). when i first made the list i didn't feel like hunting down his ref, so i just threw in a sparrow and called it a day, and then it became a bit. he's also descole's son, by the way.
do you see why it could not be a family tree. do you see what he makes me put up with. there are probably several people i've forgotten. i love this campaign.