This is Terror. Psychotic, bloodthirsty, and able regenerate from any injury, she is a deranged powerhouse of the Night Guards mercenary group.

Decades ago, Terror was a Medical Chemist by the name of Terrance Stern. Terrance had been working on a new drug to treat severe depression and he believed he made a breakthrough... he did not. For a few days, the mice he had tested it on appeared to be in a state of euphoria. However, by the end of the week, they had all perished from cardiac arrest. Terrance considered the drug a failure. However, unknown to him, his assistant had stolen the formula for the drug and begun selling it on the street as a drug called "Good Morning". When people started dropping dead from it, the assistant panicked and anonymously pointed the police towards Terrance. Terrance was promptly arrested, tried, and sentenced to Death Row. Terrance went from being respected, married, and expecting a child to only being known as a man who killed over a hundred people for some extra money.

But the worst was yet to come. There was no electric chair or lethal injection waiting for him. Instead, it was a facility deep underground. Here they tested artifacts of the old world, collected from around the world, on those who had been condemned by society. Two of the first few artifacts tested on Terrance resulted in his peculiar hair color and sharp teeth. The first artifact of notice was a simple red jade stone. Up until Terrance, this stone had killed five other people. Upon forcing him to hold it though, Terrance transformed into the opposite gender; a process that was described as "excruciatingly painful". They promised they would change him, now her, back after a bit more testing. Unfortunately, that promise would become useless after they decided to use Terrance as the test subject for an artifact known as the Heart of Gilgamesh.

They cut her open and placed the artifact around her heart. The second the artifact closed around her heart, she awoke and began screaming. The artifact activated, and the hole they had torn in her chest healed without leaving so much as a scar. From that point on, Terrance couldn't die. Bullets, fire, acid, radiation, ice, blades, nothing they tried killed her. She'd just heal. Even having her head completely removed wouldn't kill her; she'd just regenerate a new head. Worse than that, in keeping their promise, Terrance found out that she COULD NOT return to her male form. It would appear to work at first, but soon after the Heart would activate, and she would revert back to her female body. The Heart had locked her in the body she had when it was placed in her. Luckily for her, she eventually got her chance to get revenge on the scientists who had trapped her in this form and even those who had wronged her. When their so called, "Project Arsenal", breached containment, Terrance broke free as well, stealing multiple artifacts in the process. Over the next couple years, Terrance avoided the shady group, and got revenge on those who had landed her in that situation in the first place. By time she was given the chance to leave her universe altogether, the name "Terrance" no longer fit her. Now she answered to the name "Terror."

By the events of the story, Terror is physically about 200 years old. She's actually been biologically female longer than she was male.