I went with Atlas and P-Body. Here's their application.

[hider=The Duo]
[b]Name:[/b] [color=0072bc]Atlas[/color] and [color=f26522]P-Body[/color]
[b]Gender:[/b] Technically ambiguous, however Atlas is seen as the masculine one of the duo, and P-Body is the feminine one.
[b]Age:[/b] Estimated 2 years.
[b]Game:[/b] Portal 2, of the franchise by the same name.
[b]Appearance:[/b] [img]http://vignette2.wikia.nocookie.net/half-life/images/9/9d/Atlas_P-body_fhp2.jpg/revision/latest/scale-to-width-down/270?cb=20110519013122&path-prefix=en[/img]
The blue, spherical one is Atlas. The orange, eggy one is P-Body.
[b]Equipment:[/b] Each of the robots carries a standard Aperture Science Handheld Portal Device, however with minor color differences in the portals shot by the gun itself.
[hider=Portal Gun Brief Explanation]
[img]http://vignette1.wikia.nocookie.net/half-life/images/b/bb/Aperture_Science_Handheld_Portal_Device_Portal.jpg/revision/latest/scale-to-width-down/270?cb=20110519012833&path-prefix=en[/img]
The Aperture Science Handheld Portal Device (Which we will be simply referring to as a Portal Gun from here on out) was a device advertised and marketed in the late 1950s. It shoots two different colored portals onto flat surfaces, allowing objects to go through one portal and come out the oppositely colored one. The item also retains all velocity kept while going through the portal, and in laymans terms: Speedy thing goes in, Speedy thing goes out. It can also be shot at the moon and cause a small miniature vacuum into space.[/hider]
[b]Abilities:[/b] They are robots that (in Aperture Laboratories) can be re-assembled with the same knowledge retained before. Unfortunately, they do not have that luxury in this setting. They can ping a marker for the other robot to see though.
[b]Weaknesses and Limitations:[/b] Aside from being robots that lack any form of intelligent language, speaking through various beeps and gestures, they cannot use any magic or extraterrestrial powers. Because robots.
[b]Personality:[/b] Throughout their testing experience, they have both grown to take on human traits that normally cannot be expressed from robots, like hugging, playing rock-paper-scissors, and even taking a minute to break down some tasty dance moves. As a unit, they value friendship above all else, allowing them to be the embodiment of a perfect testing duo. Sometimes they do pick on eachother, though.
[b]Backstory:[/b] 
As the two test-subjects for Aperture Science's Cooperative Testing Initiative, Atlas and P-Body have spent a vast majority of time together through solving puzzles. Initially meeting in the Cooperative Calibration chambers so their "mother" GLaDOS could analyze their teamwork and see if these two robots are truly fit for the job of working together. Turns out, (they are unsurprisingly). Through the several-dozen chambers they did inside Aperture Science, then the very few chambers where they were outside of the main testing course. Under GLaDOS' direction, the two companions opened a vault that contained a very large population of cryogenically stored human test subjects, and GLaDOS claimed that the duo "saved science".

About a week later. GLaDOS fucked up and killed all of the humans, resorting to Atlas and P-Body to become "killing machines" in order to take out who was currently in charge of the facility. Once Atlas and P-Body took out a major threat to GLaDOS' well being (a bird), GLaDOS took the eggs in the birds nest to raise proper killing machines. Atlas and P-Body were thanked, however. 

[b]Entry Point:[/b] Finished the Art Direction testing initiative, then were split when taking the elevators to try and beat their personal records on solving the chambers.
[/hider]