So I think this is a good place to update y'all on this
With the new story of Hero's Oath: Sophmore Year coming out, being a sequel to the first 2, we're going to have some new villians. One of those villians has the hero name "Copycat"
Here's his appearance, obviously his look is inspired by Hitoshi Shinso from MHA (OG artist is @overjimaruid on Twitter i believe)
As you might be able to guess from the name, Copycat can copy the sollertia of another person. Like, full-on just look at someone, tell that they have a sollertia, and flat out copy their DNA and put it into his own, with this altered DNA staying in him for over a year before he looses that persons sollertia
He'll likely have multiple keys, one of just his base with no copied abilities, and one with the abilities he copies throughout the story. Or we'll do something like "(blank) normally, up to (blank) with copied abilities", which might look a bit better