From what I understand, his Tyranny isn't even a troll, so idk. Also, I don't technically think it's possible for blood to be "rainbow" since it'd mix up, but maybe iridescent?

Of course the Tyranny is not a Troll, but he may be a kind of Lusus? Although according to another ask I got… (Continued in the next Ask)

Also, I mean, nothing wrong with weird cutesy Fantrolls, just do whatever you want.