Right. Friend Esten has gone through a bit of a metamorphosis. Long story short.
After a series of unfortunate events and circumstances, Groenveld was presented with the opportunity to eat a soul.
Normally speaking, he would have banished the thought. This time however, sorrow and a lust for vengeance got the better of him.
In Lahja's world, eating a soul as a mortal will grant some sick ass power, but it comes with some costs.
One of them involve getting turned into some foul demonic version of yourself.

Whoops.