This pic was not meant to be this. It wasn't even meant to be something close to this. But I prefer this idea.

Originally, it was a scene with Pickles saying something derogatory about Warlock, who was doing something stupid in the background. Jester was supposed to look like he was just craning his neck back to look at Warlock in bemusement, but he ended up looking a bit shocked. I wanted pickles to be casually whispering in his ear, but he ended up looking just evil, like he was really saying something spiteful (as he probably would).
I hadn't liked the way Warlock had looked right from the get go, so in a moment of apathy, I just took a huge eraser and removed him completely from the picture.

It then changed the whole picture, and I thought 'what could pickles be picking on Jester about? Of course, Grudge.' And the fact that its a night scene and grudge would look cool just glowing in the background helped sway me.

Of course, Grudge does not exist, its only Jester who can see him, ever, under any circumstances. This isn't one of those 'he always told us he existed and we never believed him but lo and behold, one day we saw it too!!' things. No. Grudge is an hallucination completely created by Jester's head, he has no physical form, and he is never 'there' really.
Jester has whiskers, you may have noticed. Several reasons: firstly, he has always meant to have whiskers, as he'd be some kind of odd rat if he didn't (faith excluded *cough*) but they're white, and fine, and so subtle that you likely wouldn't see them in most pictures so I leave them out and ask you in all cases to just assume they're there.
Secondly, I don't know if you've ever seen an angry or just shit-scared rat, but they push their whiskers completely forward, its very odd but very endearing. I wanted to get him doing that.

Its porphyrin around Jester's nose, not blood.
If you have rats, you know what porphyrin is.
If you don't, clicky: http://www.ratballs.com/RatTails/Tails081.html