Gaila was an Orion female and a cadet in Starfleet Academy in the alternate reality. While studying at Starfleet Academy in San Francisco in the mid-to-late 2250s, she shared accommodations with Nyota Uhura, who felt that she invited young men back to their dormitory too often.
In 2258, Cadet Gaila had a near-sexual encounter with Cadet James T. Kirk. She told Kirk that she thought that she loved him, to which Kirk replied, "That is so weird." Their moment was interrupted when Uhura returned early from her work in the long range sensor lab. Gaila, having promised Uhura she would stop bringing men back to the dorm, attempted to hide Kirk under her bed, but Uhura discovered him and kicked him out.
Shortly thereafter, Gaila was among the cadets gathered at Kirk's hearing for his supposed cheating on the Kobayashi Maru scenario. The process was interrupted by a distress call from Vulcan, which necessitated a fleet of Federation starships to be put together at the last minute. Many cadets, including Gaila, were called into service for what was believed to be a mission of analysis and assistance. Gaila was obviously excited about the starship to which she was assigned. (Star Trek)
Gaila is never explicitly referenced on-screen as an Orion; that information comes from production materials. The character was played by Rachel Nichols.
Unlike past Orion women, who had black hair, Gaila had red hair. The decision to give her that hair color was made by Barney Burman, who was also involved in designing her makeup (as well as those of other aliens in the film Star Trek). "I gave her red hair because she looked hot with green skin and red hair," laughed Burman. He first tried the look on a picture of a girl who had porcelain white skin and bright red hair. He downloaded the image from the Internet and experimented on it with Photoshop, changing the female's skin color to green. "When [Makeup Department Head] Mindy Hall saw that," Burman remembered, "she said, 'Yeah, they [Orions] have to have red hair!' We pitched that to production and J.J. [Abrams] loved the idea!" (Star Trek Magazine issue 155, p. 57)
According to writers Roberto Orci and Alex Kurtzman, Gaila worked in the computer lab, which is one of the reasons Kirk was interested in her. Kirk became involved with Gaila to gain access to the computer for the Kobayashi Maru simulation. In a scene deleted from the final cut of the film Star Trek, Kirk sent Gaila an e-mail which launched a virus into the simulation computer containing his "cheat patch", allowing him to beat the scenario.  During Kirk's hearing, Gaila is clearly visible in the audience, with her arms crossed at all times; in the DVD audio commentary for the film, this was stated to be a holdover from the previous scene, as she is quite upset with Kirk for using her in such a way.
Screenwriter Roberto Orci said Gaila could have escaped the life of an Orion slave girl because "there's an underground railroad and some of the Orion slave girls got out and they were sold to freedom."  This might be seen as contradicting a depiction of Orions established in the Star Trek: Enterprise episode "Bound", wherein Orion women use pheromones to manipulate humanoid men.
Gaila's fate is unknown, as it is not clear what ship she was assigned to. If it was any ship other than the Enterprise, however, then she was very likely killed when those ships were destroyed by the Narada at the Battle of Vulcan. In a deleted scene, Kirk tries to apologize to her, but mistakes another female, red-headed Orion Enterprise science officer, played by Diora Baird, for Gaila. A green-skinned cadet can be seen in the background among the group of cadets who witness Kirk's promotion to captain of the Enterprise, and it is unknown whether this is Gaila or a different cadet (such as Diora Baird's character from the deleted scene).
The film's novelization – including the aforementioned deleted scene – mentions, in passing, how the attention Gaila receives from the Human technicians is "visually and chemically unavoidable," yet being around her for any long period of time could be "downright dangerous," suggesting that she emits the same pheromones as the women in "Bound".