If there's a chance you've played any of your Undertale characters in another game, wethelost is an SOL/fantasy CRAU game with an Asriel and a Toriel. There's a loose overarching plot that involves helping a child god grow, learn, and shape the world, as well as help to solve the mystery of an illness affecting the gods. Character actions and decisions heavily influence the world and there are worldhops to different worlds every three or so months where characters get to help out another world in some way.

It's a small game (we hover around 40-50 characters) and we're slow-to-medium pace with a good amount of backtagging.