As previously announced, James Callis is coming to FlashForward in a "big role."

Now, in an interview with Zap2It, Sonya Walger (Olivia Benford) also describes the character Callis plays as a "strange guy." She also goes into detail about a plot development to come:

"[Olivia]'s roped into the FBI, she starts helping them with the investigation," Walger said. "Then she meets a strange guy who knows an awful lot about her future. There's this man who's had multiple flashforwards. So he becomes a big part of unlocking what's happened, both in global terms and in terms of Olivia."

How/why does this man have multiple flashforwards? The actress wouldn't say.

But Walger did dish a bit about the status of her marriage.

"Mark starts really disappearing down the rabbit hole investigating the Mosaic... so their marriage is not in a good way," she said. "There's trouble and strife at home."

FlashForward returns with a new episode on March 18.

Matt Richenthal is the Editor in Chief of TV Fanatic. Follow him on Twitter and on Google+.