Two of last night's tribonds have been solved and one has not. Thanks to everyone who made guesses and especially
mrs_bombadil and
rhrsoulmates who posted the correct answers first. Here's a hint on the remaining one:
3. Draco...Dolohov...Aberforth
They all [blank] someone's [blank]. (Keep it clean!!!)
Joie
ETA: I thought of another one:
4. Filch...Arabella Figg...