you were warned, "tomorrow" has come, heralding the arrival of Portal 2: Lab Rat. The first issue has been posted over on IGN, spanning 14 total pages.
The comic is more than a prequel than anything else. Actually, we don't want to give away too much, but we will leave you with this little nugget: Companion Cube kills Dumbledore. We know, we know -- who woulda thunk a cube could wield a wand, let alone gain admission into Hogwarts?!