Rebecca Bois, formerly Rebecca McGill, was Chuck McGill's wife and a famous violinist. It is assumed that Chuck's disease began after his separation with Rebecca.
In a flashback set in 1992, Rebecca and a hypersensitivity-free Chuck, prepare dinner. Chuck apologizes in advance for the guest they’re expecting: Jimmy, whom he describes as “an acquired taste.” Rebecca isn't worried, but they come up with a plan in which she will tug on her earlobe if she tires of Jimmy's antics and wants to end dinner early. The couple is interrupted by the doorbell. Six-pack of beer in hand, Jimmy looks at the house in awe. Chuck impatiently invites him inside.
Over dinner, Chuck boasts about Rebecca's impressive career as a concert violinist. When Jimmy awkwardly brings up their wedding, Rebecca kindly changes the subject and asks Jimmy about his first week in the mailroom at HHM. The conversation lulls to an uncomfortable silence, so Jimmy begins telling lawyer jokes. Rebecca smiles, genuinely amused. As Chuck heads to the kitchen to retrieve dessert, she jumps in with a joke of her own. Rebecca and Jimmy dissolve into hysterics, both too preoccupied to notice Chuck pulling at his earlobe, his fake smile beginning to falter.
While reading in bed later that evening, Rebecca tells Chuck that he shouldn't have worried so much. As she turns back to her magazine, Chuck takes a crack at a lawyer joke of his own. It falls flat. Rebecca humors him with a polite chuckle, then resumes reading. Chuck stares straight ahead, jealous of Jimmy’s natural charm and the effect he had on Rebecca -- one that Chuck couldn’t replicate. ("Rebecca")
It is later revealed by Jimmy that Rebecca left Chuck, though it is unknown why. ("Witness")
In a flashback, Rebecca visits Chuck, who she is separated from, at his house where he now suffers from electromagnetic hypersensitivity. Chuck goes to great lengths to hide his condition from Rebecca and forbids Jimmy to tell her as Chuck has no wish to burden Rebecca with his issues. However, during dinner, Rebecca's phone rings and she holds a conversation with her conductor, causing Chuck pain. Rebecca is unable to understand Chuck's erratic behavior and departs in a taxi after he knocks her phone from her hand, refusing Jimmy's offer of a ride.
In the present, Rebecca arrives at Jimmy's disciplinary hearing before the New Mexico Bar Association to the shock of Chuck who thinks its a way of getting at him by Jimmy. Having been told of Chuck's EHS by Jimmy, Rebecca expresses her sympathy for Chuck and sorrow that he didn't simply tell her earlier. Chuck claims that he wanted to spare her the knowledge of his condition and she stays to watch the proceedings. On the stand, its revealed that Chuck developed EHS shortly after his and Rebecca's divorce and Jimmy suggests that it was a result of the divorce. After Jimmy reveals that he had Huell Babineaux plant a fully-charged cell phone battery on Chuck for nearly two hours, Rebecca watches in horror as Chuck implodes on the stand and confesses his resentment for Jimmy and his desperation to get Jimmy disbarred. Apparently unable to watch, Rebecca covers her face with her hand partway through Chuck's rant. ("Chicanery")
- During the Better Call Saul Insider Podcast of the episode "Chicanery", it was revealed that Rebecca and Chuck are divorced, or at least seperated, since 1998.