Portal 2: Lab Rat is a graphic novel released in April of 2011. It can be found online and in the "Extras" Section of Portal 2. It was a joint project between Valve and established comic book artists, such as Michael Avon Oeming and Jay Pinkerton, the comic depicts the events between the end of Portal and the beginning of Portal 2.
The comic follows Doug Rattman, a lab worker at Aperture Science with a history of schizophrenia, who survives GLaDOS's attempt to murder every employee in the Aperture Science facility when she is first turned on. Sneaking through the facility, he watches from the shadows as Chell is tested by GLaDOS. Following several flashbacks of Rattman's employment at Aperture Science, he witnesses firsthand the ending events of Portal. After Chell is abducted by the Party Escort Bot, he delves back into the crumbling complex in an attempt to rescue her. Upon finding Chell, he is unable to release her from her solitary confinement and, noticing that power systems are beginning to fail, he patches her chamber into a reserve grid, saving her life while at the same time trapping her for an unknown period of time. The comic ends with the injured Rattman crawling into a cryo-unit and putting himself to sleep.
The comic was released in two parts.
- On page 7, a book titled "Art Therapy - The Bennet Way" can be seen during the explosion, explaining why Doug Rattman is creating murals throughout the Aperture facility. He uses art as an an attempt to help his schizophrenia. "Art Therapy" is the name of the co-op DLC later added to Portal 2.
- On page 8, there is a message in binary at the bottom of Chell's Application form. When converted to ASCII it reads, "The cake is a lie."
- On Page 10, Rattman's statment that "he would rather have gone to the moon" may be foreshadowing of the ending of Portal 2.
- On page 13 of the comic, the Gravity Gun and Combine Health Dispenser from Half-Life 2, and the Black Mesa Health Station and H.E.V. Suit Charger from Half-Life make a cameo appearance.
- In one of Rattman's lines on page 25, he says "Both alive and dead, until someone opens the box". This is a reference to Schrodinger's Cat, a popular scientific theory involving a cat sealed inside a box.