I've been thinking (uh oh)....
Lando: "That was never a part of our agreement! Neither was giving Han to this bounty hunter!"
Vader: "I am altering the deal. Pray I don't alter it any further."
My question... If Leia and Chewie weren't supposed to be left on Bespin, and Han wasn't supposed to be turned over to Fett, then what exactly was the deal, in regards to Han, Chewie and Leia? Were they originally supposed to be set free? If that's the case, I don't see how Lando betrayed any of them. I mean, he didn't know anyone named Skywalker and had no obligation to help him. Han was his friend, not luke.
"The Sith always tell the truth. The Jedi lie on every convenience. Odd."