The actress told IGN that characters who debuted in original series Blood and Sand would reappear in the six-part prequel, but would be different to how fans remembered them.
"The audience might feel smart because they know what's coming, but we're still going to surprise you," she claimed. "We're still going to twist it up."
She added: "All the relationships are different. Solonius (Craig Walsh) and Batiatus (John Hannah) were actually great friends once."
Lawless explained that she was looking forward to exploring a more positive side to her character Lucretia.
"I, personally, am looking forward to seeing all of the characters as they were before they became a train wreck," she explained. "To see them hopeful, idealistic and with plans."
She also admitted that she was pleased to be reunited with her co-star Hannah.
"He's so much fun, for starters," she said "And he's really smart [and] professional. And he just helped anchor the whole production. Because we had a lot of actors for who it was their first gig ever and to have somebody like John come in and set a tone of complete professionalism was bloody wonderful."
Spartacus: Gods of the Arena will air on Starz in January.