As we reported a couple of weeks ago, Julia Stiles was in final negotiations to join the cast of Dexter in season five. Now, it’s official; Stiles has sealed the deal to appear on the show for ten episodes. Even better, Showtime’s press release includes a brief yet telling character description.

LOS ANGELES, CA June 7, 2010 – Julia Stiles has joined the cast of SHOWTIME’s Emmy-nominated drama series DEXTER. Stiles, who will appear in ten episodes in the upcoming fifth season, will play a mysterious young woman who forms a unique relationship with Dexter (Michael C. Hall) in the wake of the death of his wife. Production on season five begins this month and will premiere in the fall on SHOWTIME.

After EW revealed Stiles’ role was nothing along the lines of John Lithgow’s Trinity Killer, it was quite obvious Stiles would fill the void left by Julie Benz who plays Dexter’s late wife, Rita. However, Dexter does have a tendency to make friends with some crazy people. There was Rudy who turned out to be The Ice Truck Killer in season one, the absolute whacko, Lila, in season two and the ADA harboring a dark side of his own, Miguel Prado, in season three. At least when he buddies up with Trinity in the fourth he knows what he’s getting himself into, but could Stiles’ character pull another fast one on him this season? It could be interesting to see the actress go evil.

By Perri Nemiroff (via Deadline)