I'd like amnesia tropes a lot more if writers didn't always use that 'who am I?'/'who are you?'cliché. If I had amnesia I'd just be silently gathering information and smiling at the people I feel a connection with whilst inconspicuously checking to see if I have any ID on me. How hard is it when you're writing a character with amnesia, to just make them seem a little out-of-sorts? They could stop calling their friends my name - a sudden absence of nicknames could be a good hint. And they could only start referring to someone once another character has called them by their name in front of them. Make them casually glance around for reflective surfaces. If they keep a journal they could revise from it. Or they could accidentally trigger a magic power that they can usually control. Lift things too heavy for them, or test their juggling abilities.
As a twist 'Yeah, guys, I'm fine. Let's go save the world! But first...who am I?' rarely has impact. If you show instead of telling, you could probably have a secretly amnesiac character for quite a long time. Reveal the twist a lot more effectively a bit later on. Maybe this would only work for a character who is independent, or someone too polite to want to make a big thing about it.
