Nothing is known about Gabby's life prior to or as the outbreak began, except for she may have lived near Chesapeake Bay, Virginia.
At some time during the outbreak, Gabby eventually arrived at Monroe and settled there.
Gabby first appears when she enters the room of the The Mobjack, and unexpectedly encounters Samantha, along with her brother Greg, Michonne and Pete. Gabby holds them at gunpoint with her assault rifle and calls for Randall, while visibly doubtful over what to do. After her superior, Randall, identifies Samantha as the one stealing from the community, Gabby and her crew zip-tie her, her sibling, and their assumed companions. Gabby, Zachary and Cam are told to shoot any of the four if they attempt anything.
While heading back to the colony of Monroe in a motor boat, Gabby shows interest over the contents of Michonne's bag. Randall asks her if the hostages show signs of bites, rashes and coughing. She replies saying that they are clean.
The crew arrives at Monroe, where they are greeted by the leader. Gabby glares at Samantha when Norma expresses dissaproval about her repeated theft. Norma then tells Randall to escort Sam and Michonne to the storage room, and to find somewhere for Pete and Greg, without acknowledging Gabby. The latter, frustated, shows Pete and Greg the way to an unknown room.
Gabby will threaten both Michonne and Samantha when they attempt to escape Monroe via a motorboat. This can lead to two possible paths:
If Michonne let Pete go off on his own: While holding Samantha at gunpoint, Michonne will attempt to kill Gabby by shooting her with a flare gun, but she dodges, causing her to fall into the water.
If Michonne kept Pete with her: While holding Michonne and Samantha at gunpoint, Pete sneaks up on her, proceeding to shove her off the boardwalk into the water from behind.
Then she participates in the shooting to walkers who were on an island while searching for Michonne, Samantha and Pete (Determinant) along with Randall and other members of Monroe. She is not seen for the rest of the episode.
Gabby is part of Norma's group in an attempt to exchange Randall for Berto, Oak, and Siddiq. Gabby will protest that Randall isn't worth the trouble, and will proceed to berate Norma for giving Michonne and the others another chance. Gabby demands that they get revenge for Monroe's destruction and the deaths of their fellow survivors.
If Zachary was killed: Jonas sides with Gabby, demonstrating such by shooting Berto in the head, killing him. Pete responds by killing Jonas after he tries to kill Michonne, much to Gabby's shock. She later partakes in the firefight as the walkers start attacking. She watches as Norma dies soon after the walkers start overrunning her group. She is not seen again.
If Zachary was spared: Jonas is more passive, siding against Gabby. Despite no one siding with her, Gabby takes matters in to her own hands and shoots Berto in the head despite protests from Jonas, Norma, and Zachary. She will then shoot at Michonne, but misses. This results in Pete shooting Gabby and killing her in Michonne's defence.
Upon bringing the hostages along the Fairbanks house gate, Gabby begins to protest that just handing the crew of the companion over is ridiculous as Michonne made all of Monroe homeless so they all have a right to kill her, but Zachary goes against her claim thus defending Michonne and so Norma tells Gabby to be quiet.
After some conversation with the trade and possibly having already handed Siddiq over, Gabby then begins to grow more impatient and claims that Randall is not worth having brought back with the trade of three people who are friends to the woman who destroyed their home and killing people in the process so they should be allowed to have their retribution. Despite Norma's orders along with Jonas and Zachary's begging she ignores them and shoots Berto in the back of the head, killing him instantly. Norma tries to even things out at this point but Gabby decides to take matters into her own hand by trying to kill Michonne, after firing her rifle at Michonne she misses and is shot in the head by Pete, which ends with a terrified Jonas and a shocked Zachary.
The scenario can take place differently if Michonne signals Paige to shoot Norma while the latter attempts to cool the situation. After the Norma is wounded, Janey will be seen panicking, whereas Gabby will be prompted to attempt to shoot Michonne after their leader has been attacked. Equally, she will be killed by Pete.
This list shows the victims Gabby has killed:
- Berto (Determinant)
- Samantha Fairbanks (Possible Indirectly Caused, Determinant)
- Randall (Indirectly caused, Determinant)
- Possibly unnamed people (Direct or Caused)
- Numerous counts of zombies.
- "After everything they done,you're still giving them more chances!"
- —Gabby to Norma[src]
Gabby was demonstrated as being loyal to Norma, following her orders and defending Monroe in her name. When conducting the trade for Randall though, she displays defiance, shooting Berto dead despite Norma's pleas. (Determinant) If Norma is shot, she begins shooting at Michonne and company in her leader's defence, exercising a strong loyalty to her
- "Randall isn't worth all this shit."
- —Gabby to Norma about Randall (Determinant)[src]
Gabby isn't shown interacting with Randall much though she respects him as a second in command enough to follow his orders. When conducting the trade for him though, she doesn't care for him, too overcome by a vengeful passion for retribution. She disregards his safety, indirectly causing his death when she kills Berto. (Determinant)
- "You've already stolen our shit, you're not taking our boat too."
- —Gabby find Michonne stealing a boat.[src]
Gabby held a strong hatred towards Michonne for what she did to Monroe. When conducting the trade, Gabby (through sheer rage) shot at Michonne in an attempt to kill her despite the high risk, showing the extent of her hatred for her.
- "Let him go, Gabby "
- —Zachary telling Gabby to let Siddiq go. (Determinant)[src]
Although she doesn't interact with Zachary much, she respects him for being a member of the group. If he's alive when they conduct the trade, she argues with him briefly over what they should do, heavily disliking him for his resistance.
- "It's okay. We just need this to be over."
- —Jonas to Gabby about letting Siddiq go (Determinant)[src]
Gabby's relationship with Jonas is play-determined:
If Zachery is dead: Jonas is in full support of Gabby's desire for retribution, displaying such by killing Berto for her. When Jonas is killed, Gabby is greatly angered, quickly attacking Michonne and the others for doing such.
If Zachery is alive: Jonas sides against Gabby, leading the women to fight alone for what she believes is right.
- "No! Berto!"
- —Pete to Gabby about Berto. (Determinant)[src]
Gabby disliked Pete heavily, due to him shoving her in the lake or for trying to escape Monroe. (Determinant) When conducting the trade, Gabby kill Berto, causing Pete to shoot her in an act of revenge, having earned his hatred.