Cait was born in 2261 to a distant and abusive family of Irish1 descent. She had tried to run away from her parents twice; the first time, she was locked outside in a shed, the second time, they broke one of her legs. On her eighteenth birthday, Cait's parents sold her into slavery. For five years, she stole small sums of bottlecaps from her owners, until she had enough to buy her own freedom. In a pique, she returned home to seek vengeance on her mother and father and shot them both dead.
At some point after she left home, she began using psycho, developing an addiction. Sometime later, she arrived at the Combat Zone in Boston, and was hired by owner Tommy Lonegan as a cage fighter, soon becoming a strong and ruthless fighter. In 2287, a raider gang moved into the area, which then required Cait to buy friends to make life easier, making the cage fighter mistrustful of selfless offers of kindness.
Sometime later, the Sole Survivor arrives at the Combat Zone just as Cait is winning a match and subsequently interrupts the rest of the event. After the Sole Survivor defeats the raiders in the building, Tommy discusses Cait's drug addiction and offers them Cait's contract.
Telling Deacon 'Someone has to stop them' when asked if one is willing to risk some danger to stop the Institute and their nefarious schemes (this only happens after telling Desdemona that you would not take a bullet for a synth at the end of Road to Freedom).
She will try to comfort the player character if taken to the corpse of Nate/Nora in Vault 111.
Cait will dislike all four of the first set of dialogue options during the Minutemen quests to help settlements with raiders.
Cait will actively use Psycho, Jet, RadAway and other chems in her inventory. Since it was explained she was an addict when meeting her, it might be beneficial to keep her stocked up as she appears to get friendly very quickly, and it might improve her usefulness in fights.
If Cait has any Psycho or Jet, one can sometimes see her using it before completing her personal quest.
Although not always, Cait may react negatively after completing her personal quest "Benign Intervention" if the player character uses chems in front of her. She will berate them for being a "hypocrite" for using them after helping her to cure her Psycho addiction.
The Sole Survivor may raise Cait's affection level by removing their own clothing and fast traveling between safe locations.
Cait will disapprove of joining any of the factions until the second act of the main story when the Brotherhood of Steel comes in. After this she will no longer disapprove of joining the Brotherhood of Steel.
Cait asks Takahashi to serve her a drink on their first meeting, but she doesn't get it as Takahashi only serves noodles in the Diamond City market.
Cait's dialogue while exploring several of the vaults indicates that she is already familiar with the Vault-Tec experiments and the true purpose of the vault network.
When replaced by certain companions, Cait is prone to make flirtatious comments, such as Piper, for whom she will say it's "too bad they can't make it a threesome," or Deacon and MacCready, whom she refers to as "handsome." She also tells Hancock that if she ever decides to "go ghoul," he'll be the one she calls.
Without completing her personal quest "Benign Intervention," the maximum level of affinity that can be reached with her is 999. This means that to be able to get her perk "Trigger Rush," the player character has to complete her quest first.
"It all starts with two wastes of humanity I suppose you could called me parents. I'm convinced that I was a mistake, because I can't remember a single moment that they treated me like their daughter."
"You can imagine the look on me parents faces when I kicked on their door. What you can't imagine is what they looked like after... after I emptied me gun into them."
"You think I inject myself with all that shite and drink myself drunk because I’m a "tough Irish gal?""
"Heh. I dunno. Seemed quite the performance from where I was standin'."
"Rather be off murderin' a pint, but this'll do."
"Sure. Be glad to take...I mean hold some stuff for you."
"We'd move faster if you'd keep your eyes on the road and off me arse."
"Only thing better than gettin' pissed is pickin' a fight. Am I right?"
"Oh sure, make me carry more of your junk!"
"What's yours is mine... right darlin'?"
"I'm all for takin' all we can get, but you're lookin' a little weighed down there."
"Aww, and here I thought you wanted to snuggle."
"I'm glad ya took me on. Question is... can you hold on to me?"
"Damn rain is soakin' right through me clothes." – during rain
"Rounding up a bunch of escaped synths is about as much fun as catchin' radroaches. Hope you have fun with that."
"Raiders, super mutants, shamblers... you name it, they call the city home."
"Not bad... remind me to give you some pointers sometime." – after the Sole Survivor picks a lock
"I think we should be staying as far away from that reactor as possible" – After taking damage from Vault 95 reactor
"Uggh, got capped in the knee!"
When being radiated:
"If we don't move fast, we're gonna start glowin'."
"Can we quit suckin' down rads? Makin' me feel like crap."
"Let's move quick. This area isn't agreein' with us."
"That clicking from yoir Pip-Boy? Probably not a good thing."
Danse: "Just make sure you keep our mutual friend safe.", to which Cait replies: "Yeah, take a hike, Danse. This calls for a lady’s touch."
Preston Garvey: "All yours, Cait. Take care." to which Cait replies: "You really know how to make a girl feel missed, handsome."
Codsworth: "Ah, Miss Cait! So good of you to agree to take my place. May fortune favor the brave, my dear.", to which Cait replies: "You’re begginnin’ to get on me nerves, Codsey."
Dogmeat: "(curious sound)", to which Cait replies: "Don’t look at me that way, you dirty little mole rat."
Piper: "So, no one’s managed to put you in the ground yet, Cait?", to which Cait replies: "Not yet, though it isn’t for a lack of tryin’."
X6-88: "I’ll be watching, Cait. If you fail to protect this man/woman, I’ll know about it.", to which Cait replies: "Yeah, sure… what are you gonna do? Leak oil all over me?"
Hancock: "Seems I’m gonna be missing out on all the fun.", to which Cait replies: "You have no idea, Hancock… no idea.."
Curie: "I think if you travel with Cait, you may need to bring a little more ammo.", to which Cait replies: "You're just jealous because you'll be missin' all the fun."
Deacon: "And here she is, the one the only… Caaaait. Is that how they used to do it in the Combat Zone?", to which Cait replies: "I’d be glad to show you how we did things in the Combat Zone, Deacon. Name the time and the place."
Strong: "Strong find milk of human kindness on own.", to which Cait replies: "What the hell is he talkin’ about? Never mind. I don’t want to know."
Nick Valentine: "Heading out with Cait, huh? Hope you know what you’re getting into.", to which Cait replies: "Hey Valentine… I think you’ve got somethin’ on your face. Oh, it’s skin. Yeah, you might want to get that looked at."
PCPlaystation 4Xbox One Cait's quest might not trigger after her confession about her addiction. Taking another companion, sending her back to a settlement, and then talking with her should trigger the quest (it may have to do with her being flagged as a companion). For more info about this bug, read Benign Intervention.[verified]
PC Cait will talk about wanting to "lower the dosage" if she thinks she is being followed in combat after Vault 95.[verified]
PCPlaystation 4Xbox One During Cait's companion quest, Cait may begin to randomly collapse as if incapacitated during the dialogue. This will continue following completion of the quest.[verified]
PCPlaystation 4Xbox One Ordering Cait to pick a floor safe when there is an object between the safe and Cait may sometimes cause her to pace aimlessly around the area.[verified]