When he was taken by Slade, Slade knew that you were important to Robin. So when he put the probes in the Titans, he made sure to draw out your pain and make him watch if he disobeyed. As he fights you, he realizes, he loves you and will do whatever it takes to keep you safe. But when he doesn't attack, he sees you slowly fall to the ground, the pain ripping you apart.

“Okay, okay, I'll fight her! Please, just stop.”

He wished you can see the heartbreak on his face behind the mask.