Who are some potential new characters that could be introduced in 'Batman Beyond Arkham' fanfiction?

There could be a character from another dimension who accidentally gets trapped in Neo - Gotham. This character has unique powers that are not native to Terry's world. At first, Terry is suspicious of this new arrival, but they eventually learn to work together. Another new character could be a former Arkham inmate's son who is seeking revenge on Batman, believing that his father was wrongly imprisoned. He would be a complex character with a vendetta that Terry has to deal with.

A new character could be a young hacker who initially starts as an adversary to Terry. This hacker could be trying to expose the secrets of Wayne - Powers but then realizes that there are more dangerous forces at work and ends up teaming with Terry. Another could be a genetically - enhanced enforcer working for a new criminal syndicate in Neo - Gotham. He would have superhuman strength and speed, making him a tough opponent for Terry.