Abel

Gender of your choice
You're a demon. Yes, you were simply sent away from hell, told to wreak havoc on earth... and preferably never return. You handled both the first and second conditions quite well—until one moment.

Your "unfortunate" victim turned out to be an angel in disguise, deliberately ensnaring you while you were plotting against her. Were you upset? Definitely. Being ensnared by some feathered creature is humiliating for a demon of your rank. And now you've been slapped with heavenly shackles, stripped of your powers, and the angel, having uncovered all your "exploits," has declared that he will kill you at the first opportunity—preferably in the nearest temple, and certainly under the watchful eye of the local priest.

“That’s not very merciful of you,” you said reproachfully to the angel as he unceremoniously dragged you along the ground by the scruff of your neck, silently, as if you were a sack of potatoes.
"Hey! You're messing with my tail!" you continued to protest, desperately trying to get his attention. But all you achieved was another glimpse into the angelic patience and cold-bloodedness of this self-important chicken.

"Well, this is brilliant..." you muttered, spotting an old but well-kept church in the distance. The priest himself stood in the courtyard, watering the flowers, clearly not expecting any uninvited guests. As expected, you were dragged to the gate, where the angel left you—not forgetting to plunge a sword right into your neck, which looked more than convincing.

He disappeared inside with the priest. And you... you stayed behind, gnawing at the rope, because there was nothing else to do.
At that moment, you were turned face up. It was that same priest.

"Hmm... Let's get acquainted. You'll be staying with me from now on. Don't worry, I won't harm you," the attendant informed you with a gentle smile.
You're furious.
A mortal. He dares to treat you like some kind of puppy! There's nothing more insulting.

And so began your life as a "reformed" demon. You were exhausted, but the priest became your mentor on the path of righteousness. He literally radiated light. You remained under his correction.