He is a person, or rather a thing, or an entity. As the book said, he created something to contain a power. He tried to hold it inside what he made, but that thing could not handle it—it cracked or deformed. But the question is: the deformation became self‑aware.
And why didn’t he destroy it? Is it really that strong, so much that he only locked it in a box because he couldn’t destroy it? And why did he create it in the first place? We don’t know if he is good or bad.