Former O.C. star Willa Holland is to appear in The CW’s Gossip Girl for a three-episode guest stint.

The actress, who played Marissa Cooper’s younger sister Kaitlin on the hit drama series, will take on the role of 16-year-old model Agnes in the new season. Her character is introduced when she starts working for Blair’s mother Eleanor Waldorf (Margaret Colin).

Meanwhile, John Patrick Amedori has been cast as Aaron Rose, a new love interest for lead character Serena (Blake Lively), according to E! Online. As well as starring in The Butterfly Effect, he has also appeared in a variety of US dramas, including Law & Order, Nip/Tuck and Ghost Whisperer.

Gossip Girl’s second season premiered on Monday in the US. It will continue for a full 24-episode run.

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