Yay Weighted Companion Cube! He was my favourite "character" in Portal aside from GLaDOS. I'm sad I had to incinerate him, but then again, "All Aperture technologies remain safely operational up to 4000 degrees Kelvin." So maybe there's a chance he's still alive (no pun intended).
"There was even going to be a party for you. A big party, that all of your friends were invited to. I invited your best friend, the Companion Cube. Of course, he couldn't come, because you murdered him."
-GLaDOS