The Repentant Devil

"He looks younger than most Devils, but he is significantly older. His gaze is blank and yellow, a wall against speculation. He grooms his sideburns artfully, and knows how to be tactful with less seasoned members of the crew.:

"Control what something consumes, and you control what it is. The feeding of stars is a delicate art. I had spent centuries in cultivating them, studying their palates, watching for evidence of their responsive growth. I had influence. Now, how much can any Devil say the same?"

-The Repentant Devil

The Repentant Devil used to be the best of his kind at purifying souls. If soul purification is the same as cooking, which technically it is, then he was the Gordon Ramsay of soul purification: excellent at his job, but extremely critical to those who couldn't do it right. He thinks the devils of Carillon, for instance, are "incompetent".

He hid with the Baroness of Hell after the Devils' rebellion against the Judgements failed. He left his companion, but later returned to cut off her leg. After this, he visited the Iron Republic, but was never satisfied and now regrets most of his life choices.

Currently he is being chased by an unknown faction that's trying to forcibly hire him. He kills some of his pursuers, not only because he regrets his past, but also because they keep trying to pay him with unremarkable souls.

Who or what is trying to hire him?
The Judgement of the Blue Kingdom, The Sapphir'd King. It wants the Repentant Devil to refine souls for it. He's just that good.