Just to set some ground rules on my take on baby Tails so we're all on the same page. First of all I always imagine Tail and Sonic meeting when Tails was 3/4 and Sonic 10/11 (both are homeless kids best they can do is guesstimate ages and roll with it). And our little guy Tails, is the sweet, kind, caring Tails we all know and love. BUT as a baby all of that was buried under the weight of being abandoned, harassed, hurt, half/fully starved and bullied starting from maybe basically birth if not shortly after. So baby Tails is just the most FERAL of little guys. He WILL bite, claw, kick, pull fur/feathers/whatever they got and do whatever it takes if he feels cornered and threatened by someone. And yes he has his inventions even at that young age to protect him somewhat, but he's still a baby and can only build them out of the scraps he finds, so they are little flimsy and get destroyed easily by said bullies fairly often. So bitey time's are aplenty for baby Tails.

Now luckily when Sonic meet Tails one of their first interactions was him saving Tails from bullies so he started out a few steps on the less feral side of Tails. Not that Sonic doesn't/never saw this side of Tails, it just never got it directed at him unless he startled Tails or was calming Tails down when something else brought out that side. I also like to think that Sonic and Tails were together about a year before Eggman ever even found out about Tails. So by the time Eggman and their other friends meet Tails, the feral side of Tails has been pretty much put to rest as, through Sonic's help, Tails doesn't need to rely on that 'cornered feral rabies filled racoon' fight instinct anymore. The Tails they first meet relies more on his inventions, smarts, and how Sonic taught him to fight.

SO getting to the bread and butter of all this.

Sonic, Tails and Co. are fighting Eggman or maybe another villain per their usual shtick. And when they go to hit Sonic with their "ultimate weapon" it ends up a whole whoopsi daisies situation and hits Tails instead. Now readers choice on if this de-ages Tails or switched older Tails with younger Tails, but result is the same either way. The smoke clears, Tails is still there, to everyone's short lived relief, but there is now a much smaller scruggly looking Tails in that spot

(Now another thought I had just for ultimate angst potential for either scenario of scruffy baby Tails, is that baby Tails has the starved figure, scars, cuts, bruises, matted/patchy fur he had on what ever day he de-aged to/switched with)

The villain then dips cause plan has gone sideways and Sonic and crew are now just left with a tiny little baby Tails. (and the crew I imagine is Amy, Knuckles, Shadow, and Rouge - maybe Blaze, Silver, Tangle and Whisper too just to make it a really party if you want)

I think before even Sonic can react though Amy is the first to make it to baby Tails. Now I love Amy to death but bless her heart she has a tendency to get tunnel vision sometimes (big mood). So before she registers that baby Tails is a bit more ruff around the edges than she's used to, she just sees a cute little tiny baby Tails and immediately goes for the hug cause Tails is adorable on his own but tiny Tails is serotonin directly injected into your veins and her being a whole mood cannot physically stop herself from going for a hug. Plus they've met a younger Tails before so she thinks it's a similar situation so free hugs all around. (Sidenote - I'm just gonna call baby Tail BT for the rest of this cause it long)

Unfortunately BT only registers 'person coming at them fast and getting close' and just uses his reaction to bite Amy all the while hissing and growling like a feral cat in an alleyway.

Immediately everyone is taken aback (except for Sonic) cause that's not a very Tails thing for Tails to do especially to friends even if he's scared.

(And another side note here cause lord forbid my thought process stays cohesive for five minutes - but I see baby Tails being either a Tails that has met Sonic but only has been with him for maybe 2-3 weeks if even that long, so he recognizes Sonic but doesn't really trust him yet. Or for even more 'oh this is sad' it is a little Tails before he met even Sonic, so everyone is starting at the -100 trust line with the feral fluff ball. (i'm moving forward with this with the 'BT knows Sonic but no trust between them' one cause older brother Sonic is my weakness and BT being cute and clingy will not leave my brain))

So BT gets startled at everyone being startled and moves to take off to go hide in a hole somewhere cause "WHO ARE YOU PEOPLE" (if you get the reference let me know) and everyone then makes a move to catch him. Now BT is on fight/flight instincts only and does not even register Sonic. Plus Sonic does not look like the one he knows so he doesn't even recognize him in this state, just is trying to peace the fuck out of there and get to safety. And with everyone now after him BT then proceeds to go into FULL FERAL MODE on all of them.

He is clawing at them, biting everyone, hissing and spitting while making a B-line for what he thinks is an exit. With everyone still being shocked, not wanting to hurt him and with BT being more slippery than grease on pig, they are STRUGGLING. He is giving then the runaround. They're are now all getting more injured than they did in the fight that caused this. All their abilities are doing nothing in helping them catch Tails. BT is that one scene of Jack Jack from the Incredibles levels of fucking them up and he can't even shape shift. He managed to rip off one of Shadows skates, bite through Knuckles gloves, scratch up Rogue and set off her bombs (she threw them all away from her before they exploded), Amy's hands and arms are COVERED in bit marks, and he went for Sonic's shins with deadly accurate kicks (Sonic would be proud if it didn't hurt so much). They all just look like they got into a fight with a wood-chipper and miserably lost but nope it's all just a scared toddler that can and will fuck someone up.

It's only when Sonic shouts "MILES!!!!" at Tails that he finally stops (maybe Tails isn't being called Tails yet at that time so Sonic has to say his name or maybe it's just big brother/parent mode voice gets through to him). BT stops his frantic exit relay race but will not let anyone close and is still straight up growling at everyone. So now they're all just standing in a lose circle around BT not wanting to take their eyes off him but all desperately sending mental vibes to Sonic to take care of this cause what the fuck has gotten into Tails.

Cue soft big brother Sonic stepping up to bat and everyone watches him try and coax a tiny scraggly Tails, that looks 3 seconds from trying to bolt again, to get closer to Sonic and calm down. He does succeed after about 10 mins and gets BT to let him get close enough to look over his injuries. And they watch Sonic look over BT's injuries with the softest of big brother looks but when he's got BT turned around to check his back Sonic gets just a flash of anger but resigned look on his face. Cause Sonic knows those injuries and they weren't from the beam BT got hit with. (He'd forgotten how bad they were due to time and also being so young when they first met but now he's even more pissed off and sad about it) - Meanwhile people on West Side Island "why do I suddenly hear Kellin Quinn singing??"

So from there the crew moves out with BT almost glued to Sonic's side cause he's scared of everyone. Sonic has to fly them all back cause BT is too little to reach the pedals of the plane (to the surprise of a few of their friends cause they either forgot/didn't know Sonic could fly a plane also idk how to fly a plane but my imaginary one has pedals now). Finally they get back to a safe area, Tail's workshop, and the other's stick close but outside so they don't overwhelm BT while Sonic spends time cleaning/feeding/treating BT's injuries and put him to bed.

Once Sonic's got the little orange terror to go to sleep he gets everyone rounded up to talk about this and figure out how to fix it. But not before they all grill him for info cause what the fuck has gotten into Tails, they thought it was just the beam at first that caused BT to act like that but Sonic knew what to do so that theory jumped out the window. Cue Sonic giving them the watered down version of his memories of feral baby Tails, cause a lot of it ain't their business in his mind but they also need to know enough to not trigger BT into going full feral scared mode on them.

Even with what they know is the more sanitized version of events Sonic gives them everyone is shocked to find out this was actually how Tails was as a little baby toddler guy when Sonic first found him. Cause they all know how sweet Tails is. The difference is night and day. They are all also immediately mentally planning murder. (- Meanwhile people on Westside Island again "why do I hear Tyler Smyth now???? wtf??")

They all just get sad and angry cause who could hurt Tails (exceptions being made to this rule for Eggman and the rest of their circle of villains cause villains gonna villain).

I imagine Amy just starts crying cause she's upset that, that happened to Tails. But also she about to bust out that hammer and hunt some people down.

Knuckles is upset and suddenly feels really guilty about some of those early days fights he used to get into with Sonic and Tails when they all first met. But also recalling some small moments where a hint of this came out when he first met Tails but never to the extent he had seen earlier that day.

Rogue already kinda knew about it cause..spy, but not the full extent. Her info was coming from second hand sources that tried to hide the fact that they were so cruel to one of the only people who can/has stopped Eggman. She already got names and faces and she's about to get a bunch of new stuff when she robs all of them blind. And she's also planning on taking Omega with her, let him cause some chaos, blow up a few thing for fun-sies.

Shadow about to march up stairs, pick up BT, tell Sonic "this is mine now" and march out with a new brother. Also pay a little visit to Westside Island with Rogue cause he knew that face she made, she already has names and he wants in. Tails just reminds him so much of Maria and BT got Shadows 'thought to be long gone' protective brother instincts kicking into overdrive now.

The rest of this goes down with all of them just spoiling the hell outta BT, getting told stories from BT about his life and it just being one of the saddest things they ever have heard ever, and figuring out how to fix it by hunting down whoever did it to MAKE them fix it.

Bonus points: They also get to see how destructive BT is with weapons and learn:

1) why Sonic ban Tails from making some types of weapons.

2) that Sonic actually has the patience of a saint for a little destructive BT

3) Tails is way more down to murder than they had previously thought