He let you stay out of jail because he figured on using you some day.

Your day of usefulness has arrived.

If I could rope Collins without you I'd do it.
But I can't play a waiting game.

You've got to introduce me and stand by until I tip you off to go!" Cooper squirmed in his seat.

He might revolt at the other's assumption of authority over him, but he was aware that in the end he would surrender.