One of my new fave convos in the game is when having Heck as Handler during the Finale and you get to the part where you get outside and the helicopter he had called in to get us out gets shot down. Not quite a word for word repeat of it but it goes something like this...
Heck: Thorton, I got good news and bad news
Thorton: Whats the bad news?
Heck: That was our chopper that was going to get us out
Thorton: Ok, whats the good news?
Heck: I took out high value insurance on it
Heck has so many good lines, like his version of the line Mork says in Mork and Mindy "Heck calling Thorton, Heck calling Thorton, come in Thorton!" (or it might actually be mork calling thorton hehe) and also "Danger Mr Thorton!" said in similar vein to the robot from Lost in Space.
I think all the characters are good in their own special ways but Sie is probably my all time favourite out of the lot though. Everything about her is great, convos, emails, the romance scene and of course her humming 'Ride of the Valkyries' during the lift in the Embassy