Chell, the silent protagonist of the Portal series by Valve, is the main player character in both Portal and Portal 2. She is speculated to be the daughter of an Aperture Science employee. Chell's appearance is based on Alésia Glidewell, with a redesign in Portal 2 that underwent several changes during development, including a laboratory-hat variant. As a first-person perspective character, Chell is only visible through reflections and portals in the game.
Chell was generally well-received by critics and gamers, with many people praising the fact that she does not speak and looks like a "normal-looking and normal-dressing woman" in contrast to many other female characters in first-person shooters.
In Portal, Chell undergoes tests overseen by the AI GLaDOS. She defeats GLaDOS to escape but is dragged back by the Party Escort Bot. Chell's origins are unclear, with speculation about her adoption and possible ties to Cave Johnson, Aperture Science's CEO. In Portal 2, a science fair poster hints at her connection to Aperture. As a first-person character, Chell is glimpsed occasionally through portal reflections. She appears in Lego Dimensions with her portal gun, and in a Fall Guys costume holding a portal gun.
In Portal 2, GLaDOS returns to her role as test monitor in a ruined facility after being reactivated by Chell and Wheatley. She openly displays her contempt for Chell, aggravated by the endless cycle of her own death due to a quicksave system. After Wheatley seizes control and betrays them, GLaDOS ends up in a potato battery, revealing Wheatley's original design as a "moron". Chell and GLaDOS team up to escape, and along the way, GLaDOS learns her origin from former CEO Cave Johnson's assistant, Caroline, who was forcibly uploaded into her. Despite Wheatley's attempts to kill them, they manage to thwart him, ultimately launching themselves onto the moon. GLaDOS seizes control of the facility, deletes Caroline from her system, and decides to let Chell go, acknowledging that the easiest solution is often the best, and sparing Chell's life because it's "hard" to kill her.
Wheatley, an "Intelligence Dampening Sphere," is created to hinder GLaDOS's decision-making by injecting poor judgment. He aids Chell's escape from Aperture Science, inadvertently reactivating GLaDOS in the process. Chell and Wheatley sabotage GLaDOS's systems but Wheatley's newfound power drives him mad. He transfers GLaDOS's consciousness into a potato-powered module, sending Chell and GLaDOS plummeting into the facility's depths. GLaDOS reveals Wheatley's true purpose as a "tumor" meant to control her with bad ideas.
As Chell and GLaDOS ascend from the depths, Wheatley's mishandling of the facility triggers a core reactor overload. To stop it, GLaDOS must reclaim control from Wheatley. Coerced by GLaDOS's programming, Wheatley subjects them to deadly tests in his "Wheatley Science" facility. Chell and GLaDOS escape and attempt to reverse the core transfer by subduing three faulty personality cores. Despite Wheatley's attempts to stop them, Chell uses gel spillage to attach the corrupted cores and initiate the transfer. However, failsafes fail, causing a roof collapse. Chell opens a portal to the Moon's surface, dragging Wheatley through. GLaDOS regains control and restores the facility. In the epilogue, Wheatley floats in space, remorseful and tormented by a space personality core's ramblings.
Cave Johnson makes his debut in Portal 2, voiced by J.K. Simmons, with his image featured in paintings throughout the game. He communicates with protagonist Chell through pre-recorded messages, detailing the history of Aperture Science and his declining health due to exposure to moon rocks. Johnson muses on the concept of transferring human consciousness into a computer, suggesting Caroline as a candidate, ultimately revealing her as GLaDOS. An alternate version of Cave Johnson is also featured in the Portal 2 update, Perpetual Testing Initiative.
J.K. Simmons revisited his role as Cave Johnson for various projects, including Lego Dimensions, Dota 2, and the Steam Deck tech demo Aperture Desk Job. In Lego Dimensions, Cave's consciousness resides in a Personality Core, while in Dota 2, he serves as a guest announcer. In Aperture Desk Job, set years after his death, Cave's personality resides in a giant computer within a stone carving of his head.