Desperate Fight

Ren looked half-dead and shouldn't be able to stand much less fight. But the truth was Ren only suffered minor wounds and small scratches. Fean who was given the seed of the ORIGIN was indeed strong, stronger than the current Ren, but that was all he had. He was just a beast with strength. All his attacks were linear, with a lack of techniques or feints.

Even though Ren could barely dodge them, he managed to avoid getting any critical damage. He was only bruised all over, with some minor cuts on his hands.

...

Fean's barrage of attacks was neverending which gave Ren little to no time to catch his breath. The situation was unfavorable for him in every possible way, but instead of showing a negative emotion Ren's face was brimming with joy.

The tension of death if you make one mistake. The concentration needed to find that one chance for victory and the tenacity needed to keep on going even though winning was close to impossible.