AU, and non canon. Subtle personality shifts may be evident, but I'll do my best to avoid them =) First time writing for a TV series, so don't be too mean ;)
She never overdosed, that day after Sid stood her up to chase after Michelle. Why? Well, she simply never got the chance. That's what happens when you've got friends like Chris. They can get smashed and baked every day of the week, but they know what to mix, and what should never be combined. He single-handedly saved her life that afternoon when he stumbled across her.
A friendly face, a promise to wash away any and all emotions that didn't belong in the perfect world, worked like magic. Cassie drank so much her mind and soul numbed, blurring Sid like fresh ink smudged against a page. Chris encouraged it, becoming equally liquored up. It could only ever be in such a state that he would delve into her personal reasons behind the will to forget.
Cassie spilt her heart on the floor, and Chris couldn't help himself when he too let some of his memories fall amongst hers. They were soaring alone - just the pair of them trapped in the stars of bliss. It was as though, under that glossy ignorance, they both recognized the other as a person who would never share a single word passed between them. That would strike deeper than any other betrayal.
Her heart was torn, but she knew it wouldn't break anymore. Chris had made sure the stitches would always stay - maybe not always well - but at least they were there.