In his early life, he was an undocumented "street kid" from one of the Earth's megapolis cities. Though unschooled, Gil likely showed a remarkable aptitude for mathematics and spatial reasoning since at ten. He often broke into a local scrapyard to dismantle and repaired destroyed shuttle engines. In time, he was caught and "sentenced to a steady job."
Gil's expertise eventually brought him off-world, to numerous colonies across the Milky Way. His unconventional work drew the attention of Vetra Nyx, who agrees she was always on the lookout for new contacts. Vetra claims she persuaded Gil to join the Initiative: Gil claims he won Vetra's Initiative clearance in a poker game, and exchanged it for a guaranteed seat along with his friend Jill.
During the course of the game, Kallo Jath and Gil will bicker about the modifications Gil has been making to the Tempest. Kallo believes that Gil is disrespecting the planning and effort his team made to perfect the design of the Tempest while Gil believes that his redesigns are necessary to adapt to the problems of the Pathfinder's mission. Pathfinder Ryder can side with either Kallo or Gil. Eventually, Kallo offers an olive branch to Gil by offering him the Tempest's schematics that he committed to memory. Gil and Kallo find common ground in appreciating the artistry of the Tempest's design and working together to innovate the Tempest.
To romance Gil, you must be a male Ryder. The option to flirt occurs almost immediately upon meeting him and Gil appears receptive, later admitting that he was attracted to Ryder the moment he saw him. Once Gil has been flirted with several times and the mission Hunting the Archon is completed, Ryder will receive a message inviting him to Prodromos for a meeting with Gil and his best friend Jill. Before she arrives, Gil asks Ryder what he should refer to the Pathfinder as: his friend who likes to flirt, or as his boyfriend. At this point, Ryder has the option to kiss Gil. When Jill arrives, she asks about Ryder's "intentions" with her friend.
Eventually, when the Ryder goes to speak to Gil, he suggests heading to the Pathfinder's quarters where he tells him that he's serious about a relationship and wants absolute trust, something he's never had previous relationships. He puts his hand on Ryder's leg and the Pathfinder offers reassurance, agreeing that they should always be honest with each other. Gil then starts moving his hands over Ryder's chest and down towards his crotch, saying that they're both "worked up" but tells him that they only have to do what Ryder is comfortable with. At this point, Ryder has the option to sleep with Gil, telling him that he trusts and wants him.
Afterwards, the two lay in bed and Gil says that Ryder is making him a better man before asking if it's too early to start using the L word. Ryder can either declare his love, which Gil will reciprocate, or tell him actions speak louder than words, to which Gil will smirk and say he prefers a man of action.
At some point following this scene, Gil will come to Ryder with news that Jill wants to have a baby of her own and has asked him to be the father with the intention that she will co-parent along with Gil and Ryder as the baby's dads. The Pathfinder can either support this or not.
After the final battle against the Archon, Gil announces that Jill's fertilization was a success and she is now pregnant. He declares his desire to call the baby "Meri" if it is a girl or "Dian" for boy, with Ryder immediately noticing the reference to humanity's new home Meridian. He can either say that the choices are a great idea or mock Gil's names, to which he responds that they have nine months to think of a new one. He tells Ryder to be careful for the sake of him and their baby, to which Ryder can respond that thinking of them is the only thing that gets him through.
After talking to Ignacious on the Nexus:
Received after rescuing the Moshae:
- Sara Ryder can flirt with him, but he tells her that "Liam's more my speed".
- Gil was written by Neil Pollner.