Clint had no way of fighting Loki's comands he was no more than Loki's slave right now. Even when he had moments he tried to fight, it hurt and Loki would make sure he never broke free of his control.
So when Loki had made him capture Natasha that was what he had to do. Despite his feelings for her. But the man wasn't actually able to feel bad for doing it or know he was wrong. 
Being under control made it too hard to feel that way.

He had taken her back to where Loki was hiding out. Which was some abanonded building. Clint followed what ever it was that Loki wanted him to do, even if it was simple things like getting the crazy god food. It wasn't like Loki could easily do that , people were afraid of him. Sometimes even threatening them made it hard.
It seemed almost as if Clint was a different man. Loki had sent him out again for something.

So it was Loki who opened the door. He smirked seeing Natasha chainned up. "Ah perfect." He smiled darkly, The god looked rather amused. He wanted to make sure that Clint killed her, Capturing her was sure to make that possible. "Your parnter has done good work chaining you up."
The god grinned evilly. "Your not getting away this time and Barton will fufill his role." LOki was really tormenting her. He knew she couldn't do much when she was handcuffed. The god didn't even need his staff.