The plot for "Gotham" season 2 is slowly taking shape as a series of recent teasers shows several interesting details that will play out in the new season.

In the latest trailer, Jim Gordon's (Ben McKenzie) ex-fiancée Barbara Kean (Erin Richards) is seen locked away in the city's Akham Asylum after she shifted from being a cheating girlfriend to a psychotic murderer last season. 

The clip shows Barbara sitting alone in the asylum. She is later on joined by Jerome (Cameron Monaghan), who seems to be interested in getting to know her. Both Barbara and Jerome have something in common, since both killed their parents last season. But as Jerome tries to scare Barbara, she isn't fazed. She's now someone who's confident and doesn't get easily intimidated. 

Barbara's transformation from being a lying girlfriend last season into a ruthless and confident character is possibly building her up to become one of the most infamous villains in the Batman franchise. And since Jerome is believed to be the character that will later on transform into the Caped Crusader's mortal nemesis Joker, Barbara Kean could possibly end up as the future Harley Quinn. 

Yet aside from the hair-raising scene between Jerome and Barbara, the promo clip titled "Rise of the Villains" also shows the other infamous criminals in Gotham City. It includes Oswald Cobblepot (Robin Lord Taylor), who got instantly powerful as the city's only remaining mob boss, and later on turns into the vicious Penguin. It also shows Edward Nygma (Cory Michael Smith), the forensics expert turned murderer, and the twins Tabitha (Jessica Lucas) and Theo Galavan (James Frain), the criminal pair who will add to the already mounting job of the GCPD. 

"Gotham" season 2 will premiere with the episode titled "Damned If You Do" on Monday, Sept. 21, on FOX.