Making a placeholder here while I’m thinking about it.
It would be nice game-wise if Darren filled in some of the skill gaps we have; combat and pilot skills particularly leap to mind, and it makes sense that someone with interests in those directions would not immediately mesh well with the other PCs. I’m torn on the idea of him having Leadership given the impression he’s made so far, but on the other hand that might actually be the problem.
On the other hand, leaving us lacking a critical skill and wishing we had it might be fun.
For some reason I find myself actually wanting to like Darren. Which, with these PCs, is probably going to be unfortunate for him.
Quick and dirty aspect ideas:
Part of the NM in-group
Bully and/or social butterfly
Aggression looking for release
Desire to fit in or to be the best
Something about his skillset
Something about his history with NM
Maybe something about hi having made an ass of himself yesrerday.