He hadn't 'bargained on' how his new position in the company would change the way people treated him. [=he was surprised by how his new position changed the way people treated him]
You're allowed to go to the football game tonight, but I expect you to 'keep your side of the bargain' [=do what you agreed to do] and clean your room.
They've agreed to turn the land over to the state, and the state, as its part of the 'bargain', has agreed to keep it undeveloped.
(..) I've brought a little power from mine. This is time. Endless, looped time. Oh. Dormammu! I've come to bargain. Actually, I can. This is how things are now. You and me, trapped in this moment, endlessly. Yes... (..)2016 Doctor Strange
(..) Beyond time... Strange! He's gone. Stephen Strange has left you and surrendered to his power. Dormammu! I've come to bargain. Your world is now my world, like all worlds. Dormammu! I've come to bargain. No, this is real. Dormammu! I've come to bargain. (..)2016 Doctor Strange