wow, dead on.

http://castleinanity.blogspot.com/2010/12/mxpw-vs-frea-chuck-vs-intersect-pilot.html?showComment=1291869928717#c1438702598233959944

Ayefah: Sarah's wildcard factor is that once a mission gets personal for her, all bets are off, because she has an utterly vicious temper. And for a while there, she was so out of touch with her own feelings that things could get personal without her even realizing it. (That's certainly what happened in the pilot.) Now she's on a much more even keel...unless you take away her boyfriend/lodestar, in which case it's killin' time.

And yes, I do find that mildly creepy, just like Chuck's security-blanket dependence on Sarah is creepy. (Kidding! Sort of.)

But the real wildcard on the team has always been Chuck, because everything is personal for him, and he always cares more about people than principles. That's why orders slide right off his back. But since he doesn't have a vicious bone in his body, he wears it less scarily than Sarah does, even with 2.0.