The character was introduced into the series as a fellow prisoner of the protagonist, Michael Scofield (played by Wentworth Miller), at Fox River State Penitentiary. As the leader of a white supremacist group, T-Bag is the most villainous of the Fox River Eight. In the second season, the character's storyline veers from the main plot as a separate subplot. As the series progresses, more of the background story of the character is revealed. T-Bag is described by TV Guide's Maya Schechter as "one of the creepiest characters on television" and is mentioned by Entertainment Weekly as one of "TV's best villains".
As an adult, T-Bag starts committing more serious crimes such as battery, assault, attempted murder, murder, rape, and kidnapping. He quickly becomes the leader of the Alliance for Purity inside Donaldson Prison in Alabama and under his leadership the gang becomes so powerful inside the prison that the warden disbands it and sends T-Bag to Fox River.
Prior to incarceration at Fox River, Bagwell eludes the authorities and pursues a relationship with a single mother named Susan Hollander, who has two children of her own from a previous marriage. This was one of the storylines featured in the first season's flashback episode, "Brother's Keeper". Upon learning that he is a wanted murderer and rapist (by watching America's Most Wanted), she notifies the police. T-Bag had genuine feelings for Susan and had tried to change, but her betrayal prompts "that old dirty bastard [to come] right back home".
Upon seeing that there are no Alliance for Purity members at Fox River, T-Bag starts a new chapter of the gang; its growth grants him significant influence within the prison. An open bisexual, he has no qualms about seeking sexual gratification from other inmates, often preying upon younger men.
T-Bag is introduced to the series as the leader of the aryan gang inside Fox River. As a rascist and a pedofile, he is detested by most other inmates, such as John Abruzzi (Peter Stormare), or Benjamin Miles "C-Note" Franklin (Rockmond Dunbar), but his status within the Alliance for Purity protects him from attacks. Upon the arrival of Michael Scofield (Wentworth Miller) at Fox River, T-Bag wants to ensnare him as his personal plaything, but is unsuccessful. During a race riot in episode "Allen", his cellmate and lover is fatally wounded. Believing Scofield had done it, T-Bag seeks revenge but is stopped by John Abruzzi, who has his goons assault T-Bag, sending him to the infirmary after which the character is absent for two episodes.
Returning in the episode “Riots, Drills and the Devil”, T-Bag instigates a full-scale riot, during which he accidentally learns of the escape attempt and threatens to tell the other inmates if Michael and the others do not include him; the others have no choice but to agree. At the end of the riot, T-Bag defies the orders of Michael and Abruzzi and murders a guard that could expose the escape. He later frames his friend and fellow aryan gang member Trokey for the murder. T-Bag then becomes a fully fledged member of the escape team, blackmailing them to include him.
T-Bag is initally an endless source of friction on the escape team, testing the others patience with rascist taunts, and is a constant strain on Michael’s concience. Throughout the season, T-Bag is shown as having a sexual interest in other inmates, and coerces his new cellmate Seth into a sexual relationship. After Seth hangs himself, T-Bag moves on to harass newly arrived inmate Tweener, who had allienated himself amongst Fox River’s prison population. However, Michael, who was feeling guilty about Seth’s death, finally confronted T-Bag with a crobar to the knee and told him to leave Tweener alone.
When the group discovers that they have one too many for a successful escape, Abruzzi gives T-Bag an ultimatum in the episode “Odd Man Out”: back out of the escape or die. T-Bag also learns that his cousin James Bagwell and his son had been killed and is deeply upset. Knowing that Abruzzi was behind it, T-Bag sought revenge, and later slashed Abruzzi's throat with a knife, but failed to kill him. T-Bag was among one of six inmates included in the first unsuccessful escape attempt in the episode “End of the Tunnel”.
T-Bag is more loyal to the team in the season’s later episodes, contributing to keep the escape tunnel hidden and engaging in reluctant relations with a transexual inmate to futher the escape plan. In the episode Bluff his skills at rigging a deck of cards also helps the team. Upon learning that Abruzzi has returned to the prison, T-Bag is frightened and makes a second attempt on Abruzzi’s life but is stopped by C-Note, who reminds him that Abruzzi is providing their transportation. Abruzzi claims to have forgiven T-Bag, but the two characters keep a wary eye on each other for the rest of the season.
In the penultimate episode of the season, T-Bag escapes from Fox River with Michael and six other inmates. In order to ensure his safety, he handcuffs himself to Michael, knowing that it will keep Abruzzi from killing him. However, Abruzzi finally gets his revenge when he later chops off T-Bag's cuffed hand with an axe, seriously wounding him and leaving him for dead. Despites this, T-Bag manages to survive and allude capture.
The first four episodes of the season features T-Bag's journey to Utah, where Charles Westmoreland had hidden his money. Before heading to Utah, T-Bag has his hand reattached by a veterinary surgeon named Dr. Marvin Gudat, whom he murders afterwards, and bleaches his hair to change his appearance. In the fifth episode and the subsequent two episodes, he rejoins part of the main cast as the group of five fugitives dig for Westmoreland's $5 million under a garage. T-Bag tricks the other fugitives, stealing the money and begins his journey to find Susan Hollander, the woman who betrayed him. From the eighth episode onwards, T-Bag's storyline separates from the main plot which concerned the protagonists escaping and later deciding to solve the conspiracy.
In the following episode, "Unearthed", T-Bag is captured by Brad Bellick (Wade Williams) and Roy Geary (Matt DeCaro) after hiding the five million dollars in a locker at a bus station. The next episode follows Bellick and Geary's torture procedures of T-Bag as they try and discover where T-Bag had hidden the money. After he admits the location to them, they use plastic handcuffs to attach his wrist to a radiator. However, after T-Bag escapes in "Bolshoi Booze" by re-severing his hand, he kills Geary, who betrayed Bellick and took the money. Before leaving with the money, T-Bag frames Bellick for Geary's murder.
T-Bag eventually locates Susan in the last episode to be aired in 2006 in the United States, "The Killing Box", which served as one of the episode's cliffhangers. In his next two appearances of the season, T-Bag holds Susan and her children hostage in their home in Ness City, Kansas. He takes them to his childhood home in Alabama in "Bad Blood", where he reveals that they are his "salvation" and that he wants to rebuild his home, and become part of their family. Susan rebuffs him, however, saying that she is not able to love him. T-Bag is heartbroken by her rejection and finally leaves them, calling the police to release them from his home.
Beginning from the eighteenth episode, the next part of T-Bag's storyline concerns his decision to travel to Thailand. After taking the identity from a therapist he deliberately kills, T-Bag buys a ticket to Bangkok and boarded a stop-over flight from Chicago, which coincidentally was the same plane Bellick is flying in. T-Bag recognizes Bellick at Mexico City International Airport in the episode "Sweet Caroline", and is forced to hide, consequently losing his money in the luggage carousel. He then grapples with a security guard in an attempt to retrieve the money, but fails to overpower him or retrieve the money. He runs away as security footage of him fleeing is transmitted on a Mexican news station.
After narrowly avoiding Sucre and Bellick in the episode "Panama", T-Bag travels to the titular country; there, he murders a prostitute who insults Susan. During an unseen encounter T-Bag is coerced by Agent Kim into aiding the Company's plot to capture Lincoln and Michael, who are also in Panama.
Kim's plot fails in the following episode, "Fin Del Camino", however, and T-Bag finds himself being chased by Bellick, Sucre and Michael. He escapes Bellick by shooting him in the leg, but is captured soon after by Sucre and Michael. T-Bag escapes once again by stabbing Sucre in the chest with a screwdriver but is followed by Michael to an abandoned house. After Michael refuses T-Bag's truce (feeling responsible for everyone T-Bag has killed since escaping from prison), the two fight. Michael ultimately apprehends Bagwell by viciously impaling his remaining hand to the floor and leaving him for the Panamanian police. He then is transferred to a Panamanian cell, where Bellick is also imprisoned. T-Bag is last seen screaming in a Panamanian jail, a man from the Company leaving him imprisoned. T-Bag is the fourth member of the Fox River Eight to be taken down by the authorities, and the first member not to die upon interception.
Imprisoned in Sona along with Michael, Bellick, and Mahone, T-Bag is once again able to charm his way to an easier prison life than most, ingratiating himself to Lechero, a drug lord who is the most powerful man inside. Michael soon blackmails T-Bag about his pedophiliac past, in order to gain access to Lechero's cell phone. T-Bag gets Michael the cellphone, but when it is put back Lechero notices that it had been moved. In order to deflect suspicion, T-Bag gets Lechero to question the loyalty of his right hand man, Sammy, who has been openly hostile to T-Bag. Lechero is successfully manipulated into enlisting T-Bag as his personal spy, increasing T-Bag's position in the prison hierarchy.
T-Bag then gains the trust of Lechero's head drug smuggler and dealer, Nieves, only to then kill him by suffocating him with a plastic bag. He also covers up his murder by making it look like a drug overdose, and as a result replaces Nieves on Lechero's crew in the prison. He also protects Sister Mary Francis when the guards enter Sona, developing a liking for her in the process. When she steals Lechero's money, he diverts blame from her on to him and is punished for it by Lechero.
Later, when James Whistler is accused of murder and set to be killed, T-Bag attempts to 'help' Michael by asking him to frame his rival Sammy for the murder but Michael refuses to go through with it. When Michael and Whistler were caught trying to escape Sona twice, T-Bag became suspicious and figured out that Michael was trying to escape. He blackmails his way onto the team but, along with Bellick and Lechero, is tricked by Michael and captured to allow the others to escape.
After the escape, he is tortured till he says Fernando Sucre knows everything that happened about the escape. He finds the bird book that Whistler dropped and puts it into his pocket. He then is taken back to Sona and forms an ambitious plan to kill Lechero. He tricks Lechero into supplying $50,000 for an "escape" and then smothers him in front of a shocked Bellick. T-Bag then goes to the masses and hands out part of the $50,000 to all the cons. He begins the chant "all cons are equal" and ingratiates himself with everybody, leaving T-Bag as the new ruler of Sona.
T-Bag attempts to carry on his charade as the "top salesman in the Northeast" for Gate Corporation, while spending most of his time at Gate trying to decipher the contents of Whistler's bird book. Eventually, another sales manager exposes him as a fraud, and he quickly flees the Gate building before being arrested. While packing up his belongings at his apartment, he is surprised by Gretchen Morgan, holding him at gunpoint demanding to know who he is. Gretchen ties him up and interrogates him for his role in obtaining Scylla.
After that, he takes TrishAnn, the secretary from Gate Corporation, hostage to lure Michael and company to him. He holds Bellick, Michael and Mahone at gunpoint, but Mahone escapes. T-Bag wants Michael to figure out the contents of the birdbook and it's relevance to Scylla, which he believes is worth millions of dollars. They eventually discover the book contains blueprints to the Gate Corporation building, including a path to the spot within the building where Scylla can be decrypted. While forcing Michael at gunpoint into the secret compartment, T-Bag is surprised by Mahone, who along with Michael, capture T-Bag and lock him in a utility room to await capture and return to Fox River Prison.
The character's sexual interest ranges from men to women and children. When asked about the character's sexuality, Knepper asserts, "We're not passing judgment. We're not trying to get these people off the hook. T-Bag's not a homosexual. He's a raw animal. He'd [sleep with] anything."
Knepper has stated that, "Around episode 6 or 7, I got so many letters from people saying, 'When I first started watching this show, I absolutely hated you and I wanted you dead. Now I still want you dead, but I'm starting to feel for you.' I think there's something in my eyes, a childlike thing in there. There's still an innocence. There's still a bit of hope".