My character probably joined getting caught up the same thing the group got caught up in at some point. People associated him with you all, so he had a shared enemy. At some point, his destructive magic was deemed useful enough and, as long as no one bossed him around, he was pleasant enough. Dorash uses destructive arcane magic, and doesn't really care about fire vs lightning vs acid or anything like that, though fire seems easier to destroy with than most elements. He learned to make his magic less harmful to his allies, as dead allies mean he is more likely to die as well.
[ +- ] background
Hobgoblins have a training regiment called the School of Devastation, where hobgoblin devastators are trained. He was an extremely promising student, but he had a fatal personality flaw: he didn't take orders well. In most militaries, you are taught to be a cog in the military machine. ONly those with tenure and rank can really think for themselves. Dorash didn't have the patients to spend years being ordered around to get that tenure and rank, so he took some supplies and ran away. The hobgoblins that taught him want his head for that, and he doesn't care as long as he stays on the move.