Unedited. For spoilers, see title.
It's a funny thing, being dead.
It reminds him of a comic in the Sunday morning paper, the kind he could have had delivered to him in bed if he'd actually cared about what happens in the world. But those comics were never good, anyway. He gave up on them when he was still a kid. Shannon always liked them, though, so he'd save the flimsy, garish paper and pass it on to her at lunch, or whenever it was that she woke up.
When they were kids, she'd go and sleep over at her friends' houses every Friday night, come home late Saturday, and crash into bed. When they got a little older, she started staying out all weekend, only coming home to grab a change of shoes, perhaps a new tube of lipstick, nothing more. When he turned 15, he figured that there was no reason in waiting up for her anymore, and so he'd just go to bed. Wake up early in the morning, and grab the newspaper before his mom got a hold of it.
Sometimes, though, Shannon would make it back on time for lunch on Sunday. They wouldn't usually talk, after all, what was there to discuss? They had separate lives, different friends, different priorities. He could only pass her the bottle of aspirin for her hangover, and leave the comics outside of her room.
What happens on the island seems similar to high school. He's asleep (he's dead, come on) and she stays out all night with Sayid. When she comes back in the morning, he stands by her and watches, as the waves take the place of aspirin.
A few times, he wishes he could be free. The island doesn't want to let him go, though, and so he's forced to watch Shannon and the others live what's left of their lives.
...It's a funny thing, being dead.