Note from Chica: Xoph and I do not consider this canon to our characters (the two who are test subjects), just so you know.
"Hello, and welcome to the Aperture Science Computer-Aided Enrichment Center. You and one other subject have been selected to perform in a series of tests that that will require utmost cooperation if they are to be completed. Failure to cooperate with each other will result in one or both of your unfortunate deaths- and you aren't robots that can simply be rebuilt- so it's advised that you can learn and get along with your partner well. Now with that said, let the testing... begin..."