Longarm just wants to help. Whether it's hauling a stuck car out of a ditch of providing covering fire for a flanking action, as long as he's providing assistance to others you'll see a big grin on his face. That is, after all, what being an Autobot is all about. Helping, saving, protecting. He just doesn't get the Decepticons. They all seem so selfish. It doesn't make sense to him why anyone would want to live like that. It would be so tiring to be such a jerk all the time.