The man called Bigger is the leader of the Fire Eaters, inasmuch as they have a leader. This doesn't mean he makes plans for them. It just means that when Bigger says to do something, the other kajinin do it and don't argue. It also means that he can punish those Fire Eaters who do something he doesn't like - but this doesn't mean they have to ask his permission before doing anything. They just have to respect his opinion.
Entered into a tentative alliance with the Magistrates based on a mutual desire to bring down the Moment's Edge Firemen.
He's personally opposed to the rise of Blue Flame and has banned anyone from dealing it within their turf.