Friendless Night is a sex worker and petty criminal that never gives anyone his actual name. Or even 'Endy' unless he's close to the person. That being said, he will tease and flirt with poor Jack.

Hope St.John-Black & Tristan Michaud were Gryffindors in his year.

Owain Edwards was his roommate and sometimes spends time in Pennyworth as he has a NPC cousin he goes to visit and help out a lot!

I have other potential connections but I don't want to overwhelm you xD