There is always cause and effect.
Price has to be paid for every action performed.
As such, seeking to take one's fate into one's own hands came with a price that at times will appear more barbaric than one might expect.
Looking at Tifa right now, Klaus knew she had paid a grave price or was in the process of paying a grave price that, from the look of things, she didn't seem to think she could pay.
Surprisingly, this touched Klaus, but for a moment.
However, looking at someone he was supposed to hate, Klaus couldn't help but feel deeply drawn to her, and he wanted to learn more about her struggles.
'I don't know how, but she helped twice. She allowed me to take back my life by understanding what a Paragon Hatred meant and how to harness it.
She also helped me fully awaken my bloodline, which, had it not been for her, would have taken me thousands of years more to complete the one requirement I was required to fulfill as a paragon in preparation for today.