Ideally, but realistically for a new character they're not going to have her fully fleshed out yet, in the same way the characters who are regs on the show weren't fully fleshed out when they were cast either. A good actor or actress takes a role and makes it his/her own. The writers develop the characters over years, and the actor/actress needs to be able to keep up and add nuance and depth to the character with what the writers give him/her. They'll probably go with the read they like best. It's the actress's job to come in and convince the producers she's the right person for the part. It's kind of a "you know it when you see it" thing. A good actress can do that. The problem with Belknap is that they cast her after a bad audition--always a mistake. A lot of people have a say in casting though. Not the writers--the writers who are executive producers do, but the writers don't have any say. The problem is that the EPs aren't the only ones with say--the studio and the network have a say, too. A lot of hands in the pot, and sometimes that doesn't result in the best choice. Usually it does--as I've said before, I think the rest of the cast is excellent, so I'm pretty confident Kaye Sullivan will be, too. In my eyes, Belknap is the exception to the rule. She's the only miscast I've seen on all three shows. In a series regular role at least--some of those stunt casting guest stars have been pretty bad!