Lyric discussion by thenothinginside 

Cover art for Cocoon lyrics by Assemblage 23

First of all, it's a well written song like PrettyLikeDrugs said, and doesn't disappoint. Moving on to my crack at it.

It's about trying to survive through difficult times. And how it affects you (depression/selfharm) the want to be alone during these times, hence; "Give me isolation just for now/I feel a hard rain coming down/I promise that I will be back soon/But for now I'll return to my cocoon."

So basically, he knows he's going to go through a difficult time, and that he made a cocoon to protect himself from this. "Cracks in the chrysalis spread out like tiny snakes"

Well, that's my crack at the meaning behind the song. ^.^