“Wha— Is this a trick question? I am evil because I am evil. I AM AKU.”

Storytime had been invoked and Aku raised his claws toward the sky

“Before the dawn of this universe, I existed between the stars and my evil was beyond the scope of your mortal comprehension. Even the gods feared me and sought to slay me, but the three of them together could not destroy all of me. 

I fell to Earth and lay dormant for millions of years until I was awoken by a foolish human Emperor in his efforts to destroy me. It was he who gave me sentience, he who gave rise to my current form.” 

And it was he who had forsaken Aku in those first moments of rebirth, a mistake Aku would never forget and would force all of humanity to pay.

“Destruction, and all that your mortal eyes view as evil, is at the center of Aku just as it is at the center of each and every universe. I have always been evil and I shall always be evil. I see no reason why I should be anything other.”

“What next? Are you gonna ask me why water is wet?”