Domino and his orchestra gave performances across the United States and Europe, including the casinos on the Las Vegas Strip. He was invited to play at the Sierra Madre, but found himself in the shadow of the casino's founder, Frederick Sinclair. Domino, consumed by jealousy, became determined to take everything from Sinclair that he held dear. He enlisted the help of his former lover Vera Keyes, a starlet who had caught Sinclair's eye. Domino introduced them to each other as part of his plan to break into the casino vault, where he would take whatever it was that Sinclair had there that was so important. However, Keyes got cold feet, so in order to ensure her continued cooperation, Domino began to blackmail her with evidence of a Med-X addiction, apparently unaware that her addiction was a result of her being terminally ill. His final gig was to be at The Tampico, but that all changed when the bombs dropped; the security holograms activated and the Gala Event turned into a massacre.
Domino survived the apocalypse and the casino's security systems, but refused to let go of the Sierra Madre's treasure, becoming obsessed with it. He would spend the next two hundred years plotting his grand heist, oblivious to the fact that Sinclair had long since discovered Domino's plan and prepared a trap within the casino vault. However, he was captured by Dog, fitted with an explosive collar, and forced to work for Father Elijah in breaking into the casino. Although his ability to obtain the treasure may have diminished with this development, his lust for it most certainly has not.
He is a quick thinker, trained with guns (specifically pistols), explosives, and knives. He is very paranoid, setting up many booby traps and hiding several 'secret stashes' throughout the Villa - perhaps understandably, considering the ghost people who inhabit it. He is also overly obsessed with robbing the Sierra Madre in revenge for the perceived insult from Sinclair, who he believes built the casino just to overshadow him.
Dean finally found an opportunity when Christine Royce appears. Christine tracked Elijah from Big MT to the Sierra Madre Casino, where she suffered the same fate as Domino. At some point, Domino locked her into an Auto-Doc in the Villa's Medical District, where her vocal cords were torn out. She later regains use of her voice when the operation is completed by the Auto-Doc in Vera Keyes' hotel room, where it is revealed that her capture was part of Domino's plan to break into the vault, as the elevator could only be activated by the voice of the long-dead Vera Keyes.
Dean Domino, entertainer, singer... thief... had his last show on the Sierra Madre stage. The heist he spent over two hundred years planning fell apart, just as the first, by underestimating his partner's strength. Not long after the Courier left the Villa, the lights in the theater shut off, one by one. Only Dean's Hologram remained on stage, singing silently to an empty room. Still... as consumed as he had been with its riches and ruin, the Sierra Madre had held him captive long ago.
Dean Domino, entertainer, singer... thief... explored the Sierra Madre not long after he was rescued by the Courier. Once he left the theater, the Sierra Madre recognized him as a guest, and many doors opened to him. He had to admit, it had been built to last. During his search, he came across the final records of Vera and Sinclair, and realized what happened the night the bombs fell. He felt strangely sad for a moment, and he had no idea why. Shrugging it off, his mind turned instead to where the Courier had come from. Vegas still survived, out there in the Mojave. Its sights, sounds... and casinos, ripe for the taking. So giving the Sierra Madre one last nod and a wink, he set off beyond the Cloud to begin again.
Dean's Hit Points regenerate slowly over time. Very few non-player characters have this attribute; the only other known ones are Mean Sonofabitch and God.
When the player is traveling with Dean, he is able to protect the player briefly from concentrated effects of the Cloud. In addition, he will offer them resistance to its health-depleting effects, reducing damage by 25%. This perk is known as Unclean Living.
When present, Dean will comment on the player every time they loot one of his stashes, often expressing that the stash is there for himself. However, he will not retaliate in any manner.
Dean is the only Dead Money companion that has a firearm as a default weapon, the other two defaulting to unarmed. This makes him a valuable aid when engaging Ghost people at range, since his ammo never runs out.
Posters of Dean appear in the Mojave Wasteland such as in The King's room and your room at the Lucky 38, and on loading screens in abandoned casinos, advertising a planned appearance by the singer.
Though Dean is a ghoul, his voice is clear and accented, not raspy like other normal ghouls.
Even though he doesn't have ears, his sunglasses stay on as if he did.
When crouching, he makes a similar comment as Raul about how it's "hell on his knees." When he is smoking and crouching, he won't bend his knees all the way.
His ego is very fragile, so the player is encouraged to take care not to bruise it when dealing with Domino, lest it carry dire consequences down the line. Expressing irritation, aggression, or contempt will earn his ire. Also, passing the Barter skill checks in his dialogues will turn him murderous later, as he takes the player's competence as a personal insult. Other skill checks not involving Barter do not affect him negatively.
Noteworthy, if the first Barter check is passed upon meeting with Domino, he will have unique dialogue for the rest of the Dead Money storyline.
When both Dean and Christine are not companions, they can initiate dialogue with each other (or at least to the extent that Christine can), and Dean will comment on her muteness by saying "You're not much for conversation, are you?" Likewise, Dean may engage God in conversation at the Villa fountain where God expresses his disdain for the ghoul for not leaving the Sierra Madre when he had the chance.
Dean seems to ignore the fact that he has the collar on (more than the other characters) and, on the rare occasion he does pay attention to it, he refers to it as a "bow tie".
Though Dean says that he has learned how to use a knife, he does not have Melee as a tagged skill.
Dean is an avid smoker. When found, he has a lit cigar in his room, and as a companion will frequently smoke a cigarette.
Dean is the only companion besides Boone who allows you to take his clothes.
If his unique clothes are taken and he is dismissed as a companion, he will automatically equip a Dead Money jumpsuit, even though it was nowhere present in his inventory.
Despite how much he talks of wishing to stay away from Ghost People, his apartment in the Residential District is brightly lit up with Christmas lights pointing directly to it.
Although in the icon for the Assemble Your Crew achievement/trophy Dean is seen to have hair, in game he does not.
Dean Domino is an amalgamation of Dean Martin, an Italian-American singer/actor/comedian, and Fats Domino, an American rock and roll pianist and singer-songwriter. Dean Domino mentions that he worked for Imperial Records, which is a real life company that Fats Domino worked for.
If the player has the Wild Wasteland trait, Dean will reference Army of Darkness when he kills a ghost person for the first time, saying "he's not dead, it's a trick. Get an axe".
When asked about the nature of the ghost people, Dean will attempt to quote (though incorrectly both times) the famous exchange between Hamlet and Horatio: "There are more things in heaven and earth, Horatio, than are dreamt of in your philosophy."