Yay! I don't know how much you want to keep with Lust and Greed, that's entirely up to you. But there's a lot of backstory there which I'm sure you're aware of. There's plenty of logs that show how he and Lust worked together, but I didn't know what your headcannon was for them. They were always kind of like mother, lover, siblings when they are together. She was protective of Greed as well as jealous over him.
And as far as Urania goes what about her and Will Shakespeare having some backstory? He'd totally fall for her!!! She's gorgeous!