Atlas



Atlas (referred to as Blue by GLaDOS), is P-body's short and stout companion, and is one of two playable android Test Subjects built by GLaDOS for her Cooperative Testing Initiative, which was devised to phase out human testing.

Gameplay-wise, Atlas is played by the host of the Co-op session; the player that sends an invitation.

Biography
Atlas is a blue eyed Core with a basic design as a typical rounded Core, and is portrayed to have somewhat more masculinity in its programming than in P-body. Along with P-body, the two bots are pitted against a series of tests built by GLaDOS herself, utilizing the many different mechanics previously encountered by Chell from the game's single-player campaign.

Development and Acting
Both Atlas and P-body are voiced by Dee Bradley Baker.

Trivia

 * In the pre-release video "Bot Trust", the prototype Atlas in the "Unilateral Force-Induced Isokinetic Breakfast Trials" wields a frying pan similiar to the ones found in Left 4 Dead 2, frying pans are also featured in Team Fortress 2 as weapons for Demomen and Soldiers and other Valve games (but as unusable physics props).
 * In Portal 2 and it's promotional videos, Atlas' name can be seen written both as "Atlas" and "ATLAS", showing inconsistencies from Valve as far as the bot's name is concerned.
 * In the early days of Portal 2, the player used to play as a different character, named Mel. She was later replaced by Atlas, with Chell being replaced by P-Body.