So like.  This was the image.  and when I saw it, the first thing that came to mind was "... And that is how I became a Warlock."  And then I figured that this probably wasn't a fiend.  the relationship felt too kind.  You don't get those kinds of expressions when dealing with fiends.  and then I figured that it was this rats' version of Death.  Vaguely feline, skull face (common with reapers), unnatural glow.  Wings that would make it a better predator.  Totally lined up with what a ratfolk reaper might look like.

And then I tried to figure out why the rat would be the way he was... and figured that he's dead.  Like, right there. that's the line, he's there.  All he needs is for death to separate his soul from his mortal body and take him to the afterlife.  But, the rat doesn't know he's dead yet.  He was wounded (There's a darker blotch on the ground below his feet I initially thought was blood), but thought that he was gonna make it.  Clearly delusional from bloodloss, but still in a good mood overall because... well.. he 'made it' and didn't think anything out of place with the giant skull cat sitting on the rock in front of him.  They converse for a bit (Usually people are afraid or angry with the reaper, they rarely get a kind conversation), and the rat even offers to share a 'celebratory drink' with him.  Reaper asked the rat what he'd do if he didn't make it, wanting to lead the conversation down the proper path, and the rat explained that he'd be upset with unfinished business.  He isn't afraid to die, knows that it comes for everyone, and no point in trying to hide from it, but just wanted to finish some things.  Help some more people.  Stop some bad people (Which, by proxy, is helping people).  The reaper has a change of heart.  Somewhat.  Decides to make a deal.  Decides that he'll give the rat some more years to do his business, or until he dies again along the way.  In exchange, he forgoes a proper afterlife, in exchange for helping lost souls cross that barrier.  "Cheers.  I'll drink to that."  And so the two share a glass of mead, and the rat goes to sleep.  Wakes up without a wound on his body, just a small trinket, a reminder of his conversation with death.