Larissa was observing Wayne Mansion when a gardener asked her what she was doing there, and she quickly took him out by jumping on his back and applying a rear neck choke. She then had him killed by her associates, rubbing his blood over her forehead and pretended to have been in a car accident which made Alfred let her in and try to help her. Selina and Bruce came down the stairs and Alfred realized she was a hired killer. The two got in a fight where her henchman distracted Alfred long enough for her to chase after Bruce and Selina. They lost Bruce and Selina who fled into the woods.
She was later seen looking for Dick Lovecraft and was confronted by James Gordon, she explained that if he stood down, she wouldn't kill him. James feigned surrender and then knocked out her henchman. She disarmed him and got into a fight with him after a short brawl, she quickly overwhelmed him and rendered him unconscious with a chokehold. She then used James's gun to kill Lovecraft.
She later got contacted by Clyde, a street criminal who had captured Bruce and Selina. She showed up with a team of henchman, Selina and Bruce tried to escape as Alfred and James showed up and got into a firefight with her henchman. She captured Bruce and asked him where Selina was. After he mentioned she was gone, she walked away when Alfred was getting close, though not before telling him he should not confuse bravery with good sense. 
As a ruthless mercenary, Larissa is willing to kill her targets. She is able to tactically deceive people and feigned helplessness to get close to her targets. She seemed to uphold some code of honor as she only killed people on the contract. Despite having the chance she did not kill or seriously injure James and Bruce.
- Peak of human physical condition: As a highly skilled assassin, Larissa is in top physical condition.
- Expert hand-to-hand combatant: As a highly skilled assassin, Larissa is highly skilled in unarmed combat, being able to easily take out a large man. She disarmed James Gordon and quickly beat him. She heavily relied on grappling moves and used choke holds to quickly render her opponents unconscious.
- Expert markswoman: As a highly skilled assassin, Larissa is highly skilled in the use of firearms.
- Even though she remains unnamed during her first appearance on the show in the episode Lovecraft, her real name and alias were revealed in an earlier report before the episode airs.
- In the comics, there have been many incarnations of the villain Copperhead. Larissa is based on the latest one, who was the only female and was introduced in the video game Batman: Arkham Origins. The name "Larissa Diaz" though, originates from the show as the character previously remained unnamed. Like Larissa, this female Copperhead is a South American expert escapist and assassin who works as a contract killer.