I missed that! That's a horse of a different color; he's probably an insured driver and, when this case gets to court, will be the nearest "deep pockets" for the lawyers to go after. And he wasn't wearing a seat belt. The fact that he was, at his age, participating in a joyride with a 12-year-old . . . he's the worst-injured of the five, but he is as responsible as anyone for his own injuries.
18 vs. 12 . . . bears comparison to a statutory rape situation. Any responsible adult would have grabbed the keys and prevented the accident in the first place.
But, your comments are interesting......you are probably right that "if", and that is a big if, he is insured, the lawyers could go after him..... Maybe someone with expertise in insurance can tell us.