You don't, but not out of mercy.

You start to press down hard, hearing Rolf's breath coming in wheezing whistles as you constrict his airway, and you grin savagely as you think to stomp down all the way and break his neck. You start to do just that...but then you stop. You stop just short of completely **** Rolf, watching him struggle for breath and staring up at you in fear as his life ebbs away from him. You take a cruel satisfaction in that, in seeing the fear in his eyes and seeing him weak beneath you. Such a deep satisfaction do you take in it that you decide that you want to let it last as you bring your foot up off of Rolf's throat, the dwarf sucking in a hoarse breath and coughing as you let him breathe once more.

He catches his breath as you stare down at him and he gives you a weak grin that is supposed to be mocking. "I knew...you were a weakling. Don't have it in you...to finish me, boy?", he gasps out and you kneel down beside him so you can stare straight into his face, your own expression full of almost serene joy.

"Oh, I could finish you, Rolf. I could...but that's too easy for you. You are defeated, dwarf. Defeated by the one you thought of as a weakling. I beat you, Rolf. Your life is mine to end when I wish and I could give you a quick and merciful end, but that's more than you deserve.", you tell him as you slowly stand up, still looking down at him, "Instead, I'm going to let you lay here and suffer with the knowledge that, as you die, it was my hand that brought you low. I want you to bleed out knowing that you were a failure as a warrior and as a man. You are nothing compared to me, Rolf. And you will die knowing I didn't think you were worth the effort of finishing off."

He snarls up at you wordlessly, but he can't do anything to you as you turn to walk away. You pause, though, and stop by his lower body. After a moment, you raise your foot up and then bring your boot down hard on his knee. You hear a loud crunch as his bones break and shatter beneath your heel, drawing a howl of pain from the injured dwarf. You take pleasure in that sound and decide you'd like to hear it once more as you go around and repeat the process on his other knee, grinding the bones beneath your boot hard enough to cause splinters of his bone to pierce his flesh from the inside out.

He cries out in agony as you do this and you look to him once more, a cruel smile on your lips. "Can't have you crawling away, can we, Rolf? No, you are going to lay there, helpless and weak, so I can sit here and watch you die and enjoy every slow, agonizing second of it.", you say and then turn away from the dwarf once more...and find yourself face to face with Asta, her hands clenched around Rolf's fallen axe and a look of fury twisting her usually gentle and pretty features into a mask of hatred.

She stands there before you and you realize that you are in no shape to fight as your right arm hangs loosely at your side, unable to move due to your dislocated shoulder, and your left hand is still throbbing and swollen and blistered from handling the dwarven longsword. You are unable to defend yourself and, as Asta starts to move, you curse as you think about what you can do.