Was Chuck Always Going To...

Screw Over Jimmy regarding Sandpiper?

I always thought so, but rewatching I'm not so sure. His initial excitement feels very genuine. I actually feel he wants to do the case with Jimmy, with him in charge. He also is so dependent on Jimmy it seems pretty much impossible for Chuck to operate without him at this point, he can barely step outside.

I think the change in thinking starts when Chuck absent mindedly walks out to the car with the files. He realises he has more independence. Then, when Jimmy says he'll "have to get an office right next to yours", we get a zoom in on Chuck's face, and I think this is when he makes up his mind- he can't let Jimmy into HHM. He can't keep him down if that happens- Jimmy will see himself as Chuck's equal, and that is intolerable.

As bad as Chuck is, I don't think he's scheming enough to build Jimmy up like that from the start, always intending to squeeze him out of his own case.