I’m never sure what counts as a trope or an au;; but omegaverse is an obvious answer to both. So I’ll say besides it, I love soulmate tropes, like soulmarks or the seeing colors for the first time take on it. Soulmates makes for good angst with such sweet happy endings. As for lulaw, I actually prefer writing cute fluffy things for them believe it or not, and anything supernatural would be my favorite kinda trope for them. I like giving them a bit of a magical twist.