Vin is the forbidden daughter of a skaa woman – who already had a son – and an Obligator – who was not a mere low ranking official but the one in charge of the entire section of the Steel Ministry devoted to preventing children like her (Lord Prelan Tevidian). Unlike many other skaa women, Vin's mother wasn't killed prior to her birth, and survived long enough to give birth to a second daughter. The circumstances of Vin's birth were traumatic enough for her to Snap – making her a full Mistborn from infancy. Vin's infant sister was a misting Seeker, and Vin's mother was insane at this point, giving Ruin a foothold to influence her actions. Ruin directed Vin's mother into an act of Hemalurgy – killing her infant daughter with a bronze ear stud and piercing Vin's ear with the empowered stud. Vin's half-brother, Reen, arrived at this point, took his sister away from his obviously insane mother, and taught her the way of the streets.
Reen's way of teaching her the streets – and protecting her from Steel Inquisitors — was to have both of them join skaa thieving crews, and beat her until she had no trust in any human left. His final 'lesson' in how humans were rotten was to abandon her himself.
Vin's Snapping at birth allowed her to burn any and all trace metals she ingested, calling it her 'Luck', which enabled her to survive in a male dominated thieving world. With her trace metals, she could Soothe and Riot emotions — making crewleaders see her worth, yet dismiss her as a threat. This enabled her to lessen beatings, and reach 16 without drawing the eyes of the Steel Ministry. It also enabled her to avoid the fate that most think of when they hear about an essentially homeless sixteen-year-old girl.
Her last crewleader (Camon) had realized her powers and would often take advantage of them when beating her. But they both slipped – first with meeting and Soothing Marsh, who was a Seeker and can tell when someone is using Allomancy near him, and second when Vin attempted to Soothe an Obligator. The first brought Vin and Camon to Marsh's attention since she hadn't been burning just one metal. Marsh then told his brother, Kelsier, about the Mistborn girl he'd seen. The second brought the attention of a Steel Inquisitor.
Kelsier's crew interceded — drawing the Inquisitor's attention off of Vin so that they could collect her — and added her to a special crew with one rather insane goal. Kelsier's Crew were plotting the downfall of the Lord Ruler himself. Kelsier was already infamous; he survived the Pits of Hathsin—a prison camp that would kill its prisoners if they could not produce a specific geode once every seven days, and was a full Mistborn.
He was the first Survivor of the Pits. That's how she met Breeze, Dockson (Dox), Hammond (Ham), Clubs, and Lestibournes (renamed Spook by Kelsier, Kell, later). Kell uses her as their noble face/spy, getting her to pose as Valette Renoux, the favorite niece of Lord Renoux. Lord Renoux was actually the kandra OreSeur, and currently contracted to Kelsier. While she was with the crew, the Mistings and Kelsier taught her about Allomancy. Kelsier taught her steel and iron, Pushing and Pulling. Ham taught her pewter. Spook gave her a few hints about tin when she asked. Breeze taught her about Soothing and Rioting, though he can only Soothe. Marsh taught her about feeling bronze pulses, to be able to tell what metals others are Burning. As there's nothing to teach about copper, she didn't spend much time with Clubs, and Dox isn't an Allomancer.
As Lady Valette, Vin is given Sazed, a Terrisman steward, as her steward to accompany her to noble balls. At her first ball, she meets (Lord) Elend Venture, the man she later falls in love with. That very night, she nearly dies by the hand of a Steel Inquisitor. If not for Sazed and her body burning pewter even while she was unconscious, she would have died then.
When Reen was still with her, he would beat her if she was too friendly, drew someone's attention, or drew the ire of the crewleader they were with. So when she wakes up to pain, two weeks after she nearly died, she thinks Reen had beaten her, even though he'd left a long time before.
A while later, Vin learns that a noble House was planning on assassinating Elend the night of the final ball - the tensions between Houses had gotten to the point that all of the politicking was over. The danger to Elend alone was enough for her to tear off her dress on a balcony and fight against two Mistborn and two other Mistings, though Vin runs because she can't even face Kelsier and win most nights and he's only one Mistborn. Earlier that night, Elend had said he never wanted to talk to her again, essentially. Because she loves him, she doesn't care. She kills or stuns the two Mistborn and the other Mistings don't - can't - follow them.
Shortly after, when Kell expresses his disapproval that she risked her life to save Elend - saying that he's a nobleman when she says he's a good man - Vin snaps at him. She says that they're all noblemen too, because skaa don't live like they do. She shames them on accident by being in a fury and telling them what she's lived through. "When's the last time you slept in an alley, shivering in the cold rain, listening to the beggar next to you cough with a sickness you knew would kill him? When's the last time you had to lay awake at night, terrified that one of the men in your crew would try to rape you? Have you ever knelt, starving, wishing you had the courage to knife the crewmember beside you just so you could take his crust of bread? Have you ever cowered before your brother as he beat you, all the time feeling thankful because at least you had someone who paid attention to you?" (432 of hard cover The Final Empire)
Vin feels bad almost immediately after, Reen's voicing telling her to be angry at herself for letting them get close and that they're all going to leave her now. Kelsier comes up to talk to her, and Vin tells him that she loved Reen and still does, despite him beating her, swearing at her, yelling at her, saying he'll betray her, and abandoning her. She continues to say everyone leaves her. She barely remembers her mother, but her mother left her too - which is why she clung to Reen. Then he left. Then, she loves Elend, but Elend doesn't want her anymore. She turns to Kelsier and asks when he'll leave her. Kell avoids answering her truthfully and completely and convinces her to go downstairs so Sazed can finish stitching up her cheek wound from the fight. She was worried about going down so soon after what she said, and he replied that if she didn't say something stupid every now and then she wouldn't fit in with the group.
Vin and Kell go to meet Marsh, but when they get there there's a lot of blood everywhere. They assume he was killed.
Kelsier kills an Inquisitor and saves Elend's life because Vin loves him. Then the Lord Ruler stabs him in the chest with a wooden spear. The skaa of Luthadel rise up against the Lord Ruler that very night and Vin kills the Lord Ruler with the help of Marsh - who was really turned into a Steel Inquisitor - and the mists. In the chaos, most of the nobility fled and Elend becomes King of Luthadel.
(The Well of Ascension) In the year between the first and second books, Elend proposes and Vin rejects the proposal. Straff Venture, Elend's father, is sieging Luthadel and later Cett shows up and joins in on sieging Luthadel. Vin spends most of her nights killing assassins sent after Elend. The kandra OreSeur is replaced by the kandra TenSoon, though Vin and Elend believe it is someone else in the crew or the household. Elend gets deposed, and she slaughters Cett's household believing that Cett's a Mistborn. After figuring out he actually isn't, she leaves without harming him.
Not long after, another army shows up near Luthadel, this one commanded by one of Elend's old friends but even more dangerous than the others because it's made of koloss. Vin kills Elend's half-brother, Zane, while he's burning atium, even though TenSoon didn't help her in the battle as Zane was his real contract holder. She came to a realization in the battle that she needs to have all the good things she can get and finds Elend. Since she had only refused out a belief that she wasn't good enough for him, they get married.
She makes them Emperor and Empress by taking down his father. Because of altered prophecies and her increased bronze burning powers, she thinks she's the Hero of Ages and lets Ruin loose on accident. The Mist Spirit had stabbed Elend in the gut in a last resort effort of getting Vin to use the power at the Well for herself. She saves Elend's life and makes him a Mistborn by giving him Preservation's God Metal, Larasium, and pewter.
So fast forward a year to the beginning of the Hero of Ages (there is very little information about what happened during the gap) and they're going around conquering cities to get to the secret storage caverns the Lord Ruler left behind.
Vin arrives by falling through the sky in a tempest of horseshoes and then immediately uses said horseshoes to kill several koloss. After frightening them enough, the Steel Inquisitor in charge shows up. With Elend's help, she kills the Inquisitor. They continue like this for a while, then Vin ends up captured by an Obligator, Yomen, that was still around after the Collapse of the Final Empire because his city had the last storage cavern.
He keeps her in prison, where she finds out the voice of Reen she keeps hearing is actually Ruin, and sets her on trial for the murder of the Lord Ruler. She tells Yomen that she is not Kell's Heir but the Lord Ruler's, and he calls her crazy and says that she is blaspheming. Then Kell's brother Marsh, the Steel Inquisitor, shows up and demands to know where the atium is.
Atium allows the burner to see into other people's futures for a couple seconds, essentially making one invincible in a battle, and it's the body of Ruin. Marsh, controlled by Ruin almost completely, becomes furious upon finding out that Yomen doesn't actually have it and fights Vin, who pulls on the mists a second time. Then Vin is let out of prison because the koloss that were formerly Elend's are attacking Elend's army. After letting Elend and Yomen sort out what they were going to do - Elend was relieved that Yomen had even let his army into the city - Vin leaves for Kredik Shaw in Luthadel to draw Ruin's attention away in a crazy idea.
There she fights thirteen Steel Inquisitors, remembering that Kell had had trouble with one. However, she had been betting on the mists feeding her power as they had on two previous occasions and ran out of metals, bleeding and feeling sluggish with the lack of pewter. Marsh broke her leg, grabbed it in an attempt by Ruin to get her to tell where the atium is, then broke one of her arms, then the other. Then he snapped her other leg, then all her fingers one by one, reached for her face while she lay screaming...and that's where I'm taking her from.
