Well, for a while, I made Modern Sonic's versions of Tom and Maddie. I think the same could go for Wade, Rachel, Randall, Jojo and the cast from the movieverse.
Tails and Knuckles (sadly) don't get adopted, because Tails is always busy with his inventions and Knuckles has to guard the Master Emerald on Angel Island.
The only one who gets adopted is Sonic, because Tom and Maddie found him injured when he was 5 years old, after he lost Longclaw.
Sonic's been with them for 10 years, until at the age of 10, he was adopted. He was unlike his movie counterpart, staying hidden for 10 years before Tom found him.
The rest of Sonic's history is the same as the games and Sonic Prime (which is now, unexpectedly, part of the Modern universe), only he fought Eggman when he was 9.
He still calls Tom "Donut Lord", because he does the same as his movie self.
Same goes for when he calls Maddie "Pretzel Lady". He mostly calls them "Dad" (for Tom) and "Mom" (for Maddie)
Sonic tried to do yoga with his adoptive mother, but had some bad experiences at first, until he learned to get the hang of it.
He comes to the Green Hill police station to check in on his adoptive father and Wade.
He sometimes dislike his adopted aunt, Rachel. He gets along well with Jojo.
He likes Ozzy and takes him out for walks with Tom and Maddie.
This meant Sonic is having a happy life with Tom and Maddie, in the Modern universe.
Trust me, we all don't know who Sonic's parents are in the games, but I imagine he was with Longclaw before she died and then with Tom and Maddie.
