It was announced earlier this year that the actress had joined the cast of the sci-fi drama as computer whiz Jess.
She told SFX: "[Jess] has everyone's back. She's got an eye and an ear for everything, so I think she's definitely someone you want on your team. I think she's very loyal too because she obviously hears every conversation, and has read everyone's files, but would never use that against them."
Kearney also said that there are "two sides" to the new team member.
"One one hand, she's very girly - loves socialising and hearing gossip and all that king of thing,"
she explained. "But when she's sitting in front of her hub in the ARC, she's the most efficient person you could ever have in that job."
She continued: "She’s a bit of a whiz kid and highly apt at computer science. She was headhunted for this job, and she was just immediately at home."
Primeval returns to ITV1 on January 1.