It's not too surprising that, with a name like Hells Angels, these guys are bad news. (Although you'll be glad to know they've cleaned up their act a little since the 1960s.)
The first Hells Angel we meet, if you can call it that, is an unnamed biker dude who danced—yes, you read that right, danced—into Norvelt from a nearby town right before he was flattened by a cement truck. The only time we see him is when he's laid out on the mortuary slab as Miss Volker examines him, but it's quite a view.
He was apparently mean and tough and a devil worshiper to boot, or so the Norvelters judge by his tattoos. He has tons of them, including a snake with "666" in its mouth and a devil's tail spiraling down one leg (9.93).
As if those didn't contain enough heavy-handed devilish imagery, he also has a gruesome meat cleaver tattoo on his chest. This one looks like "the cleaver has chopped open his flesh so you can see his open heart, which is black. And in the middle of the black heart is the laughing red face of the devil" (9.103).
Clearly, this dude was bad news, and kept equally bad company.
But: Miss Volker describes him as a "nice young man" and she sells her sister's house to him (12.56), so maybe appearances are deceiving. There lots of reasons someone might choose to get a devil's face tattooed on his chest. Right?
The other Hells Angels are (of course) mean, tough, threatening. They roll into town on their loud motorcycles (duh), wearing black leather jackets. Some even wear brass knuckles and Nazi helmets (11.31).
Not surprisingly, they're also thieves (they steal one of Mr. Huffer's most expensive caskets), arsonists (they burn down one house, and attempt to start at least one other fire), and brawlers (one aims a throat-slitting motion in Jack's direction) (11.33). Basically, they're major anarchists—but not the gentle, Emma Goodman kind. They believe in destroying communities rather than building them, and so they represent everything that's the opposite of Norvelt.