Rufus and Ivy
I just wanted to come on here and write about how completely disgusting this relationship is.
Setting aside the crazy age gap (which is an issue in itself), they were UNCLE AND NIECE before they found out she was a con. Lily told Carol that she came to love Charlie as her own, and Rufus likely felt something similar. He told Dan that she lives under his roof so he felt responsible for her. He picked up her medication for her. He cared for her. The William thing might've been nasty due to age gap, but at least she was never close to William in a fatherly way.
Them getting together is just insane and disgusting.