You are absolutely correct. Even during his Jedi career, he was always unstable and emotional; a firecracker. Now he's just got some influence from a not so nice mentor...lol.
He does, but he's obsessed with the Sith culture somewhat. He went to Korriban to hunt down a forge to create a Sword in, the very blade he uses in the Battle for the Main Gates thread. They could come across him forging it.
Would they have been on Korriban recently?
Otherwise, or possibly as well, we could wait for the timeskip and they could meet him on Tython.
I love doing RP's where the other person or I am controlling two characters.
I plan on aging him. Exactly how much, I haven't decided. Though I suspect I will land on or around thirty. When I first joined, I did not expect a timeskip and I planned on aging him as he developed. I never landed on an exact age, which actually attributed to his tribal origins in a way. But yeah, something like that.
I like the idea of Noster taking Zallek on during the beginning of this ten year gap, which might force some aging on your character. Though that might depend on when you decide to start writing with him.
Noster Eden might be a good fit for Zallek's master. If you like, I'll take you as Noster's apprentice after the TimeSkip. Maybe we can do some flashback training/mission too.