What is Sting's motivation? Why is he back?

[Nice Person]

I'd like to get your thoughts, not on a storyline but on why Sting is 'back' kayfabe wise?
He seems to be challenging HHH, but why?
Is it possible HHH was the reason Sting never signed with WWE after his contract ran out (kayfabe)?
Did HHH's political influence scare Sting away at the time?

Those are my best guesses, what are yours?
What will WWE come up with to explain Sting's arrival in WWE?

Sting will return to tell the WWE and the World that he will be undergoing gender reassignment surgery, and come back as a Diva - Stinga !

 

[Prince Bálor]

Sting will return to tell the WWE and the World that he will be undergoing gender reassignment surgery, and come back as a Diva - Stinga !

You've been obsessed with this gender reassignment surgery thing as of late.
Will you be undergoing one and you're (in a subtle way) asking for our opinion on it?

 

[Jacob Fox]

You've been obsessed with this gender reassignment surgery thing as of late.
Will you be undergoing one and you're (in a subtle way) asking for our opinion on it?

Freud referred to it as projection

 

[KITT]

Sting is there to right the wrongs like he was in WCW with the nWo. Wherever evil strikes in a wrestling organization, Sting is there to vanquish it!!!

 

[Nice Person]

You have to laugh you know - when folks can't tell that they're being 'yanked.' <w>

 

[InSaNe]

I doubt WWE will go that far back but that sounds awesome.

They pretty much did in the interviews with Triple H. Hunter mentioned something about what happened between them in the past, but after that, they kept quiet. I feel like they're withholding the drama until after WM31, where everything escalates to the next level.