Sonic, literally the hedgehog.

After Sonic was placed in that strange position and felt dizzy, Tails and Shadow ended up defeating Dr. Eggman.

Shadow: Are you feeling alright, Sonic?

Sonic: Yeah... I think so... he says, sounding a little dizzy

Tails: I'm sure the spell Eggman cast on you had something going for it... though I don't really know what effect it'll have on you... for now, I suppose you'll stay in Shadow's care.

The next day, Sonic was no longer the same in appearance. Now he was smaller, chubbier, and adorable.

In the end, they reach an agreement that Shadow will look after Sonic to see if anything happens to him.

As the hours pass, Sonic feels increasingly strange, to the point where he no longer even thinks about what he's doing.

It seems that the position has turned him into an animal, or rather a hedgehog.