A little demon that got lost in the realm of humans… one single human found that demon and treated him with kindness… disappearing after that.
The demon, in order to not forget his savior's face, took his form.
The kind human was a sick one… very weak… he already had a lover, but couldn't meet his lover again though… as he never woke up from his bed.
The devastated lover, saw the demon… then he grew obsessive towards the demon saying, 'I won't let you get sick/die' blah blah blah.
And I…
did I tell you that the ML is a priest? priest x demon type.