Why did Hans risk his life to save the resistance if he was the traitor?

He saved the resistance in multiple occasions. When the Germans first surrounded the resistance when they acquired the resources from the British, why did Hans come out of the blue to save them?? He could've easily let them die and get the heck outta there. It doesn't make any sense.

Also why would he risk his life to save Tim from prison?? And why was he shooting at the Germans instead of running away or shooting at his "teammates", he could've easily gotten the heck out of there and *beep* his way through and nobody would've doubted him.

Good movie overall though, 8/10. Flawed but overall very fast-paced and captivating..