A Quote from Portal 1
GLaDOS
While it has been a faithful companion, your Companion Cube cannot accompany you through the rest of the test. If it could talk - and the Enrichment Center takes this opportunity to remind you that it cannot - it would tell you to go on without it, because it would rather die in a fire than become a burden to you.
More quotes from Portal 1
Your entire life has been a mathematical error... a mathematical error I'm about to correct!
Please note that we have added a consequence for failure. Any contact with the chamber floor will result in an unsatisfactory mark on your official testing record, followed by death.
When I said "deadly neurotoxin," the "deadly" was in massive sarcasm quotes. I could take a bath in this stuff. Put it on cereal, rub it right into my eyes. Honestly, it's not deadly at all... to me. You, on the other hand, are going to find its deadliness... a lot less funny.
Let's be honest. Neither one of us knows what that thing does. Just put it in the corner and I'll deal with it later.
Area and state regulations do not allow the Companion Cube to remain here, alone and companionless.