How come in Sonic The Hedgehog Princess Elise don't remember Sonic anymore, but Silver The Hedgehog still remembers who Sonic is? And is a returning character in the series.

Part of me just wants to blame time travel shenanigans, and leave it at that, but to be fair, when Silver first appeared in the Archie comics, he acted like this was the first time he'd ever met Sonic, and I want to say there was a Sonic game where Silver acts like he doesn't remember Sonic. (maybe Sonic Rivals?)

Regardless, I think it's perfectly clear, at this point, that SEGA has long since stop caring about continuity in Sonic games, and are just doing whatever they feel like.

All that said, I don't see Princess Elise ever returning, especially not as a playable character. She's pretty infamous, sa pamamagitan ng this point, for being the most hated character introduced, in one of the worst games in the series, and SEGA knows this. Silver's character is largely considered the only good thing to come out of Sonic 06, and even he rarely appears, and is barely ever playable.