Much like his sister, Tommy is rash and arrogant, and mostly relies on his strength to win fights. He has little compassion for others. He makes his own rules, and is quick to anger when someone challenges him.
The twins dress and talk very much alike. Tommy has blue eyes and blond hair, with one line shaved across his temples. He wears multiple earrings. His clothing matches his sister's: he wears a white shirt with the sleeves torn off, black pants with tears on the left thigh and right knee, boots, and red suspenders. He wears a padlock on a chain around his neck. He also has black finger-less gloves.
By 2016, he has significantly bulked up in his upper body. He also has cut the top half of his hair to be much shorter, and his clothing was replaced with un-torn duplicates.
Tommy and Tuppence attempted to rob Gemini Gems in the Central City Mall. Kid Flash and Superboy tried to intervene, but things escalated and the Terror Twins took hostages. The fight eventually moved outside to the car park, where they were surprised to see Flash and Superman had also responded to the commotion. Outnumbered, they fled, pursued by Superman.
After the captured heroes escaped, they contemplated liberating the villains, but decided not to and find their captor first.
Kylstar's Vessel December 1, 23:58UTC
The Justice League, Superboy, Miss Martian's valiant effort against Kylstar convinced him to treat his sentient weapons better. All captives, including Tommy, were released, and Orb-One explained Kylstar's motives. He was a freedom fighter who was on a mission to stop slavers who destroyed his homeworld. As a sign of his good intentions, he offered to return captives unwilling to help with his fight back to their homeworlds. Those willing to stay were promised good treatment and glorious battle.
The Collector's Ship December 1, 19:01EST
Tommy, along with all of Kylstar's captives from Earth, were teleported into the Collector's Ship. With the additional reinforcements, the Collector's body was quickly destroyed.
Metropolis December 1, 19:03EST
The body was merely one of many, and the Collector unleashed several additional Coludroids on the assembly. The battle was interrupted when the Collector noticed that the probe he embedded underneath Metropolis was malfunctioning. If nothing was done, Earth would be destroyed. Since the Collector was a preserver and not a destroyer, he agreed to shut off the beam that was slowly shrinking the City. After the assembled heroes convince him of their determination to prevent him from taking the city, he begrudgingly agreed to re-size it back to normal and leave.
Metropolis December 1, 22:03EST
The Collector teleported all Earthlings into the city. The villains were nowhere in sight, and the assembled heroes thought that the Collector had teleported them elsewhere to spite them. Unbeknownst to them, the villains were actually just yards away, mentally shielded by Gorilla Grodd, who informed them they now owed him.
Tommy and Tuppence were chosen for a strike team lead by Kaldur'ahm to capture Blue Beetle. Tommy had some doubts about Kaldur's new right hand Tigress, as he had never heard of her. He shelved his concerns after she equated it with challenging Black Manta's judgment.
They located Blue Beetle outside El Paso, and attacked him and his friend Impulse. The Terror Twins held down Blue Beetle for Icicle to freeze him. It didn't hold, however, and Tommy was knocked out by Blue Beetle's sonic cannon. The two heroes got away, with the device Kaldur had to track Blue Beetle. Tommy was not happy Kaldur had hardly put up a fight, but changed his opinion when he learned the device was meant to be taken, and would hack Cave security for them.
The strike team infiltrated the Cave, and Icicle and Tommy Terror attacked Superboy in the Grotto. After a short fight, he was fitted with an inhibitor collar. Both he and Tommy expressed interest in ending his life right there, but Kaldur disagreed.
They moved on to the Mission Room, where Impulse thought he could take on the Terror Twins. After bouncing off Tuppence, he landed straight in Tommy's hands, who gave him a collar. Blue Beetle attacked him with his sonic cannon, but reneged when Kaldur held the Cave for ransom with a bomb in the Mission Room.
Tommy carried Impulse aboard the Manta-Flyer. He was already on board when Blue Beetle unsuccessfully, tried to escape. In the process, Kaldur's dead man switch detonator was revealed to be a bluff, which lead to Tommy and Icicle having doubts in the ruthlessness of their leader. That they had left Nightwing and Superboy behind alive also weighed in. To end the dissent, Kaldur ordered Tigress to detonate the bomb.
Onslaught oversaw security at a meta-human auction and arena fight held in an abandoned mall. He and his sister were guarding the prisoners until they were alerted by Devastation of intruders. After chaos broke out, he was irritated he couldn't participate in the battle before spotting Nightwing and Tigress trying to liberate the captives. Tommy was excited at the action but this distraction allowed Black Lightning to shock him and his sister. He recovered and joined in attacking Tigress and Nightwing. He tried to strike Nightwing who overcame and had the prisoners get out the building, before Tommy overpowered him and slammed him into the ground. Tommy prepared to kill him but Geo-Force and Tara came to the heroes' aid by blocking the villains' path to prevent pursuit.
Super strength: This is one of the Terror Twins' main abilities. This allows them to easily pick up or carry heavy objects. The Terrors Twins were able to battle Superman and the other powerhouses of the Justice League.
Super leap: Their strength also allows them to jump over great distances and to great heights.
Invulnerability: Both Tommy and Tuppence have great durability and are able to take punches from Superman and Superboy with very little physical damage to their bodies.
Tommy and Tuppence Terror are named after the characters Tommy and Tuppence, a couple of married detectives created by Agatha Christie. The name is also a nod to Greg Weisman's friend Tuppence Macintyre, who had previously helped him research Scottish history for the television series Gargoyles. Greg had previously created another character based on Tuppence Macintyre while writing Captain Atom: Plastique's lawyer, Tuppence Macrae.