Tell me, who is the real Monster?

Levi was created solely as a weapon for the King. Pure irony that man feared the devil himself but thought they could control him. But what happens when that Monster is touched by the love of another? It births a greater terror within him, dawned out of the desperation of love itself; twisted, bloodied, terrible and revered. Inspired by Naoki Urasawa's Monster Rivahisu and Erihisu