In many stories a character of mysterious origin has no memory of where the actually came from. But they were found by goodhearted people who befriended them and took them in. During their time together, the mysterious person discovers they have all kinds of hidden depths that with the good guys influence they start to use For Great Justice
or at least in the name of The Power of Friendship
But years later a dark secret is exposed. The bad guys own the mysterious person! All their abilities aren't For Great Justice
, they were supposed to be For the Evulz
. And now our hero is faced with a terrible choice. Do they keep on fighting as one of the good guys even if it means betraying their original identity, and potentially even fighting their real family
, or do they embrace their destiny and leave behind their good friends? Sometimes it's even worse if they're a Person of Mass Destruction
and just being alive guarantees bad things to happen regardless of their allegiance. In such cases they may be tempted to take their own life to protect the friends they've come to know and love.
Naturally a spoiler trope since this is usually a major plot twist.