Tritium is an Alexandria package cape. She has enough super strength to hold back a punch from a Titan or to punch through a building, she is ostensibly invincible, and she is capable of flight. However, her abilities come with the unfortunate side effect of being radioactive. The harder she fights, the more radioactivity she builds around herself, although she is immune to its effects. She labels her punches as 'Nuke punches' as a result.
Tritium was not aware of the side effects of her abilities, and unfortunately killed many people around her with her radioactive nature, including her family, friends, pets and coworkers. As a result she was benched for the most part, and included in important missions.
↑I knew her in the same sense I knew who a big actress like Margery Funk was: I knew her face, general history, and general personality. Quiet, reserved, and totally ill-suited for the gung-ho Advance Guard. She spent much of the time benched, jumping in only for the big, important missions. - Excerpt from Infrared 19.5
↑ 2.02.1I watched as whatever gave Tritium her invulnerability failed her. Or she’d turned it off because keeping it on would have made her lethal to everyone here. I saw as her body shifted from a dim silvery silhouette to a spiral of what looked like a red towel being whipped around in a spiral. - Excerpt from Infrared 19.5
↑ 3.03.1He emerged, rising from the liquid street with chest thrust out. Capes were more ready for him this time. An Alexandria type flew in to meet him, her fist punching his fist and stopping it from reaching down to the unprotected back lines. I recognized her as Tritium, a bench cape from Advance Guard. Strong enough to punch through a building, ostensibly invincible, and unfortunately not much of an everyday cape because utilizing her invincibility, flight, and what she now termed her ‘nuke punches’ made her radioactive. Push harder, fight more, and it built up more. She was immune, but the people close to her hadn’t been. She’d lost her family, friends, dog, and coworkers and had hurt many bystanders before the issue had been discovered by accident. It hadn’t come up in the news. - Excerpt from Infrared 19.5