In his new ABC show, "Castle" alum Nathan Fillion plays John Nolan, the oldest rookie in the LAPD. "The Rookie" just announced Fillion's new co-stars, including the woman who will reportedly play his love interest.

According to "Dark Matter" will play fellow LAPD rookie Lucy. Deadline says she "struggles with a domineering training officer and might be developing a budding romance with Nolan."

As TVLine put it, Lucy is "intelligent, confident, tough and compassionate. She hails from a family of law-breakers, and is the first member of her brood to choose an honest, respectable path. (A previous version of this story listed the character's last name as Benitez, though that will change.) During Season 1 of the new series, a budding romance develops between her and Fillion's title character, John Nolan."

(Fun fact: Melissa O'Neil is also a singer and musical theater actress who won "Canadian Idol" Season 3.)

"The Rookie" recently revealed that Afton Williamson ("The Night Of") was cast as Talia Bishop, "a newly promoted training officer who is assigned to work alongside Fillion's 40-year-old LAPD rookie." Eric Winter ("Rosewood") was cast as "an overbearing training officer." So it sounds like he might be the one O'Neil's Lucy struggles with.

"The Rookie" marks a reunion between Fillion, 46, and former "Castle" showrunner Alexi Hawley. Hawley is showrunner of "The Rookie," and Fillion will executive produce the ABC show alongside Hawley. There's no premiere date yet, but stay tuned.

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