[Goldsmack]

So I am writing a fan fict novel and i wanted to keep it "fluffy", so here are my questions

In the book there is an uprising on a planed that the PDF have to deal with, the book starts with the closing days of the war when, beaten back to the palace the leader of the rebels and his platoon of body guards are infected with Nurgels rot and devote themselves to Nurgel. 1st question is how would this transformation happen IE they get the desies and then what? pray to Nurgal and they are blessed?. 2nd question, the leader of this cult, would that make him a Champion Of Nurgel or what?

 

[normtheunsavoury]

First up it's spelled Nurgle.
Nurgle is unique among the Chaos Gods in that he doesn't really tempt his followers into worship, he gives them a fatal disease and then says worship me or die.
So yeah, as you've already said, they get infected, pray to Nurgle and they are 'saved'.
On the second question, being a cult leader wouldn't necessarily make you a Champion of Chaos, you have to do something pretty exceptional to claim that title. Chaos Champions are the great warriors or sorcerors of Chaos, anyone who runs the risk of getting his arse kicked by a guardsman would have a hard time claiming the title of Champion.

 

[Goldsmack]

Ok so its not out of the question for a human who has done great things for chaos to be granted the title of Champion?

 

[normtheunsavoury]

Not out of the question at all, the Chaos Gods would have a damn hard time recruiting if the most they could offer the average mortal was some nasty boils, a third eye and some knobbly bits.
Space Marines have a built in advantage, they are engineered to be hard as nails and are the galaxy's greatest (human) warriors, but that doesn't rule out others being gifted with amazing powers.
If that person was directly responsible for an entire planet falling to Nurgle then I would imagine that he would look favourably on his servant and gift him appropriately. Possibly even giving him the strength to challenge others apparently much stronger than himself.

Keep in mind that almost anything is possible, you just have to work a little harder on some ideas than others. If you can come up with a reason that makes sense and fits with the general themes of 40K then go for it!
Happy writing!