Kati here with two moar characters. And apparently a monopoly on the Juno PBs. It wasn't intentional!
moribund is Lisa Turpin from Harry's year. She died in the Battle of Hogwarts and is now a ghost. She mostly haunts Hogwarts but sometimes it depresses her too much to see the students so she travels around. She used to be pretty nice but now she's just pissed off and really cynical. She's definitely not a happy camper and will try to rain on your parade.
fangerbanger is Alexander Abercrombie. He'll answer to Alex but since he started dating Bella (his secret vampire girlfriend), he wants to be called Alexander. He's the son of Euan and Helena and Dominic's brother, and he's a 7th year Ravenclaw. His girlfriend is a secret but his dad (being head of Hitwizards and all) might know. He has a bit of a vampire fetish, though he's kinda a normal dork.