SPOILERS!Below is information that may adversely affect the reader's enjoyment of the game.
Troy Calypso is the secondary antagonist of Borderlands 3 and one of the two leaders of the Children of the Vault, alongside his sister Tyreen. Troy is an oddity in the series, as he is a male Siren, the only one known to have ever existed. His Siren powers were stunted due to him developing as a parasitic twin.
Troy is incredibly cruel and sadistic, much like his sister. Much of this sadism is drowned within an air of cocky overconfidence. Troy tends to behave as if everything is a game and often doesn't take threats very seriously. This is most prevalent during his boss fight, wherein he constantly insults the Vault Hunter, even as his health drops dangerously low, all the while ignoring Tyreen's pained cries and goading her into continuing in spite.
Troy was born on the Eridian homeworld of Nekrotafeyo as the son of Typhon DeLeon and Leda. He was born as the parasitic twin of his sister Tyreen, meaning he was less developed, and was born attached to her. Due to his sister being born a Siren, her status was transferred over to him, thus becoming a Siren by proxy.
At some point during their childhood, the two were surgically separated. Troy was given a prosthetic right arm and also began depending on his sister to survive.
Typhon's steady stream of stories about Vault hunting filled Troy and Tyreen's heads with ideas, causing them to leave the safe haven of Nekrotafeyo and seek their fame and fortune. The two of them would begin preying upon the damaged minds of Pandorans by broadcasting senseless murders they committed across the ECHOnet, gaining a literal cult following as a result, forming the Children of the Vault.
As the Crimson Raiders prepare to leave Pandora aboard Sanctuary III, the launch site is suddenly assaulted by the Children of the Vault, led personally by Troy and Tyreen with the intent of recovering the Vault Key. Amidst the chaos, Lilith is forced to face off against the two Calypsos by herself. While Tyreen fights Lilith, Troy broadcasts the fight across the ECHOnet. After Tyreen is knocked away, Lilith teleports behind Troy and knocks him down, where she is shocked to learn that he too is a Siren. Troy remarks that it "runs in the family", giving Tyreen enough time to subdue a distracted Lilith; Tyreen reveals that Troy is a parasite, and that she is the only thing keeping him alive as she begins to leech Lilith's powers. Before Tyreen can completely kill Lilith from the process, Troy convinces Tyreen to stop in order to give him some of the absorbed power. After making a mockery of Lilith and recovering the discarded Vault Key, the two leave her to die at the hands of their followers while they leave to check up on their deal with Katagawa Jr. on Promethea.
Once the Vault Hunters open the Vault on Promethea at The Forgotten Basilica and defeat its guardian The Rampager, Troy and Tyreen arrive after the Vault Hunters finish looting the Vault. The two thank the Vault Hunters for doing all of their dirty work in defeating The Rampager as Tyreen leeches The Rampager's power, while Troy reveals that the monsters contained within the Vaults are the source of their power. After giving Troy some of her absorbed power, Tyreen apprehends Ava, though Maya retaliates by phaselocking Troy and forcing him into an headlock, demanding for Ava to be released. Once Tyreen complies, Troy grabs ahold of an unaware Maya's arm and drains her of her powers, leaving Maya to fade away. An enraged Ava attempts to shoot Troy, only to be phaselocked by him, leaving both Troy and Tyreen to be surprised at his feat. With their mission complete and an extra bonus, the Calypsos take their leave, though not before Troy sarcastically remarks to Ava on who to call if she ever becomes a Siren.
After making a mockery of Maya's death across the ECHOnet, the Calypsos and their followers travel to Eden-6 to search for its Vault. While Tyreen establishes an alliance with Aurelia Hammerlock by killing Montgomery Jakobs and allowing her to take control of the Jakobs Corporation, Troy begins to conduct experiments with his phaselock powers on several prisoners at The Anvil. The result is the creation of his own personal super soldiers dubbed the "Anointed," powerful members of the Children of the Vault infused with his phaselock powers.
Not long after the Vault Hunters arrive on Eden-6 and save Sir Hammerlock from captivity at The Anvil, they are soon contacted and instructed by Aurelia to leave the moon, being offered a large sum of money if they comply. Using this as a means of gaining access back to his former homestead, Wainwright Jakobs tasks the Vault Hunters to play along and sends them to meet Aurelia. Instead however, they are met and phaselocked by Troy, revealing that Aurelia's deal was a ploy to get the Vault Hunters into their clutches. Troy reveals to them his mastery of his phaselock powers, more so than Maya ever could, as well as his unsatisfying place under Tyreen’s shadow before revealing he intends to kill the Vault Hunters personally. Before he can do so however, he is shot and wounded by Wainwright, who forces Troy to chase after him around the mansion, giving the Vault Hunters enough time to escape with critical information that would lead them to the Vault Key fragments of Eden-6.
Knowing that the Calypsos were after the power of the Vault monsters, Patricia Tannis devises a plan to nullify the next Vault monster's power to prevent the Calypsos from siphoning it. After locating the Vault of Eden-6 at The Floating Tomb, the Vault Hunters open it and defeat its guardian The Graveward. After its death, Tannis successfully nullifies The Graveward's power, much to the annoyance of the Calypsos, who call the act "uncalled for". However, after the Vault Hunters finish looting the Vault of the Graveward and regroup with Tannis, Troy remotely phaselocks Tannis and has Tyreen promptly warp her away.
With everything that they need, and enough Eridium at their disposal thanks to Pain and Terror's pledge drive on Carnivora, Troy and Tyreen begin the process of opening the Great Vault, located at a large set of Eridian ruins near their main cathedral. Using his phaselock powers, Troy phaselocks Elpis, revealing it to be the key in opening the Great Vault: Pandora itself. The Vault Hunters, with the support of their many allies, assault the cathedral, where they cut off Troy's Eridium supply, seemingly stopping the process of opening the Great Vault. As the Vault Hunters drew closer to the dig site of the Great Vault however, the opening process suddenly resumes, and Tannis realizes that Troy is leeching off of Tyreen's power to continue the process.
As the Vault Hunters arrive, Troy reveals himself and engages the hunters in a lengthy battle, all while opening the Great Vault and leeching power from his sister at the same time. Despite his best efforts, Troy is ultimately defeated, and laments to his now unconscious sister that they were so close in opening the Great Vault before collapsing onto the ground, dead. Ava, Lilith, and Tannis soon join the Vault Hunters, and Ava touches Troy's arm, absorbing Maya's former phaselock powers from him and becoming a Siren in the process. While the Crimson Raiders celebrate their victory, Tyreen awakens and acknowledges Troy's sacrifice, congratulating him for completing his mission and promising to continue their work "together" as she absorbs Troy and the last of his essence completely.
- Alright, let's get out of here. I wanna see if Katagawa's good on his word. Leave the scraps to the dogs.
- As a Siren, Troy also owns the characteristic wings and tattoos emblematic of Sirens in the series. However, due to the unlikely circumstances that resulted in him being a male Siren, Troy has some noteworthy differences from his contemporaries. His tattoos are naturally red as opposed to blue, and take on a much more flayed and violent shape as opposed to the more focused, swooping shapes of the other Sirens. His wings are among the largest of the sirens seen thus far, and take on a more demonic/draconic shape with a deep red colour as opposed to the bright flames exhibited by other sirens. Additionally, his left wing is larger than his right, most likely due to the fact that he was born without a right arm.
- As mentioned in an ECHO log found on Eden-6, it is believed Troy was briefly involved in a romance with Aurelia, the sister of Sir Hammerlock.