Sometimes referred to as Subject Zero, Jack appears in Mass Effect: Foundation, Mass Effect 2, and Mass Effect 3. Before joining Commander Shepard's team, she was a criminal, involved in piracy, kidnapping, vandalism, and murder. Though she's a human female, she is also biotic – and considered one of the most powerful and dangerous ones alive.
Jack was at one point kept in cryogenic stasis after she being caught. She's a borderline psychopath, often violent and anti-social, with very little filter for strong language. Her body is covered from head-to-toe in both tattoos and scars. Jack was tortured and abused all her life, leading her to trust no one. Throughout the series, her strong personality comes through in her dialogue, as in the quotes below.
10 The Plague Zone
While the team is on Omega, an asteroid filled with narcotics, weapons, and trafficking, Jack gets poisoned by Forvan. Following this, they make their way to the Plague Zone, which affects all creatures except Humans and Vorcha.
The team talks to a guard outside of the plague zone and, as long as the other member in the squad are human, Jack will say, "Plague zone, but I'm immune? Sounds fun. Let's go." Despite the Forvan poisons, she still can't be harmed by the disease-ridden Plague Zone due to being human.
9 That Was Mean But Damn Funny
Eventually, the team runs into Niftu Cal, an egotistic Volus with biotic abilities who later disappears. Then, when a squad member comments that no one mentions anything, Jack responds with, "When the chips are down, people will always sell out their friends for credits."
However, if Commander Shepard stops Niftu Cal from taking part in the fight on Illium, Jack will say, "He doesn't deserve to live," after he walks away. Meanwhile, if Commander Shepard allows Niftu Cal to fight Captain Wasea, Jack replies with, "That was mean but damn funny." No one in the squad cares for Niftu Cal much, especially Jack.
8 Scared Little Child
Jack's tragic and violent history with Cerberus dominates a lot of her interactions with Shepard in Mass Effect 2, which is hardly surprising as the group forcibly shaped her personality. As Jack herself states, "Turns out, mess with someone's head enough, you can turn a scared little kid into an all-powerful b*tch."
As a child, Jack suffered a lot at the hands of Cerberus, as the group sought to harvest her biotic potential. These gruesome experiments would come back to haunt them.
7 Take Notes From Shepard
On Illium, the team tries to recruit a Drell named Thane Krios, where they run into a wounded Salarian. The team helps him, but, Jack disapproves, saying "He doesn't know where the Assassin is."
Following that, they interrogate a mercenary and wind up tossing him out the window. Afterward, Jack comments, "I could take notes from you, Shepard." She will often remark when Commander Shepard gets violent, due to her own love of violence and danger.
6 A Lot Of Chemicals
At some point, the team arrives on Horizon, which is a Terminus colony that has substantial economic opportunities within.
Here, after they encounter the Collectors for the first time, Jack says, "Peaceful. Usually takes a lot of chemicals for me to get this kind of quiet." Perhaps she is talking about alcohol or drugs – maybe some otherworldly stuff that only exists in the world of Mass Effect.
5 Begging For A Dirt Nap
During the Found Forged ID mission at the Citadel, the human members of Commander Shepard's team will talk with the Asari. If the Council was abandoned, and Commander Shepard says, "If no one else will, yes," and apologizes, Kalara Tomi will take offense regarding the attitudes of the humans.
Jack does not respond well to this, saying, "You're begging for a dirt nap". Jack doesn't mess around, as the player knows. It's a thinly veiled metaphor for killing Kalara Tomi and burying her six feet under.
4 Crack It Open
Grunt is a Krogan, genetically engineered to be a super soldier. The team recruits him and his natural desire for pure violence. During this mission, Jack will comment at the very start: "I already want to kill this person." Later on, when witnessing Grunt in the tank, she says, "Crack it open. Let's see what a pure Krogan's got."
Jack does not particularly love Krogans; she and the Blue Suns once got into a firefight. It ended after a Krogan mercenary came up from behind her and hit her in the head, knocking her out and letting the Blue Suns take her away.
3 I Want To Shoot Someone
When the team is on the Derelict Reaper mission, they eventually get locked in behind kinetic barriers. Jack responds to the situation with, "Trapped in a Reaper. I want to shoot someone."
The Derelict Reaper orbits Mnemosyne. It has a mass effect field that keeps it together (although it is falling apart). The ship is barely functional. Though she always wants to shoot someone, Jack's hunger for violence escalates when dealing with the Reapers. These highly-advanced machines reside in dark space and claim there is "no beginning, nor end."
2 I Smelled Murder
The team will recruit Samara, a thousand-year-old Asari Justicar, on Illium. If Elnora dies during the mission, the team listens to her audio diary. During her description of the murder, Jack says, "I knew I smelled murder on that b*tch." If Elnora is spared, she laments about the team not killing her.
While Jack obviously loves killing people, Elnora was a member of the Eclipse and murdered a Volus. Furthermore, Elnora was happy after killing someone. The team discusses how she probably would have gone on a murdering spree if not stopped.
1 Too Happy With You
If Jack leads the team on the Suicide Mission, she will die in the attack from the Collector. Before her last breath, she says, "Too many...tore me up. How'd you talk me into this? Heh...I wasn't supposed to care." If Commander Shepard romanced Jack, she will further add, "I knew I'd get hit on this job. I was too happy... too happy with you."
Players can avoid this fate if Miranda Lawson suggests leading. Jack tries interjecting, but Commander Shepard immediately responds with, "No one wants to take orders from you."