The first question would be where the game lies on the scale from Pink Mohawk to Black Trenchcoat. If it's a full on Pink Mohawk game, being a Halloweener is probably going to be in the running as the "straight" runner

If your group prefers a more gritty/black trenchcoat/cloak-n-dagger/"realistic" game, being a molotov-tossing loonie could sure be problematic, of course.
Some ideas for integrating into this kind of game with that kind of background:
1) Maybe you avoided the usual fate for Halloweeners (dying of an overdose, dying in a gang war, dying in a house fire, dying in a rave that got out of hand and burned down, etc) by being arrested and forcibly separated from your worst influences by being incarcerated. Now that you're out, you still have old friends in the gang (maybe) but you're not really IN the gang anymore, because personnel turnover's a bitch in that circle and most of the gang by now doesn't know you from Jimmy the Rabbit. Being a con, unable to get a job with a criminal SIN, is easy fodder for a motivation to turn to Shadowrunning.
2) "Maybe you're not as bad as the WORST of them". Maybe you're simply not insane (yet) from imbibing random chemicals or frying your brain on BTLs. Maybe you're only involved with the gang for similar reasons many real life kids fall into gangs: safety and/or it's the only thing you can feel like you belong in. If, for example, you're an Ork, you're a grown ass adult at 12, 13 years old? Would you want to stay in middle school as a human if you were in your 20s? Easy to see why Orks don't. What do you do when you drop out of school? Can't get a job as the laws all are built for human perspectives and since humans are still children at this age, then so are you, legally! Joining a gang it is! Maybe you're a full-fledged Halloweener, but you're looking at Shadowrunning as a way off the crazy train that only has one ending that comes in a morbid variety of subtle differences. What can you offer to professional, "black trechcoat" style shadowrunners? You know the streets. You have street cred with the NPCs in those circles. What's more, with GM permission, you can easily whip up a bunch of ganger buddies to provide a loud distraction whenever the sneaky plan calls for one.