Portal 2: Lab Rat

Portal 2: Lab Rat is a graphic novel released in April of 2011. A joint project between Valve and established comic book artists, such as and, the comic depicts the events between the end of Portal and the beginning of Portal 2.

Plot summary
The comic follows Doug Rattmann, a lab worker at Aperture Science with a history of, 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. The comic ends with the injured Ratmann crawling into a cryo-unit and putting himself to sleep.

The comic was released in two parts.

Trivia

 * 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 Rattmann's lines, he says "Both alive and dead, until someone opens the box". This is a reference to, a theory involving neurotoxin and a cat sealed inside a box.