Who is Trip Fontaine from The Virgin Suicides and what is their importance?

Even though he's one of the neighborhood teens populating the suburb, Trip Fontaine is not part of the neighborhood boys who are narrating the story. He lives with his father in the same suburb, but his sexual activity and his lifestyle on the fringe keeps him apart from most of the other boys of the neighborhood. Because of this situation and that for obvious reasons he keeps most of his whereabouts secret, much of the information about him was gathered not though observation, but rather through an interview conducted decades after the suicides. By then Trip Fontaine is undergoing a detox treatment in an establishment somewhere in a desert. He is described as a victim of the excesses of his own lifestyle.