And the winner is... Brandon. But not the Brandon who made a bet with his friend, the writer James Dashner. That Brandon is Brandon Sanderson, an established fantasy novelist whose first YA effort, Steelheart, hit the bestseller lists this month. Sanderson lives just a few minutes from Dashner in the suburbs south of Salt Lake City, Utah. Coincidentally, Dashner also had a new book out this fall – The Eye of Minds, the first volume in his Mortality Doctrine series. Both books even have the same publisher: Delacorte Press.

Sanderson couldn’t resist a little friendly wager, proposing to track book sales for Steelheart and The Eye of Minds for one week in October. Whoever sold the most books would NOT have to change his profile picture on all his social media. The person who sold fewer books would have to change it – to a photo of Justin Bieber.

But when Sanderson looked at the numbers, he couldn’t help but notice that a new book by another neighbor – Brandon Mull’s Spirit Animals: Wild Born, had sold more in the same period than either he or Dashner.

“His book outsold both of ours last week, so I’m declaring him the winner,” Sanderson wrote in a blog post. “This means that both James and I have the honor of changing our social media profile pictures.”

Dashner went with a standard Justin Bieber publicity still (which he’s since changed again, to a photo of his dog). Sanderson dressed his up, perhaps imagining what the Canadian pop star’s own spirit animal might be (see below).

(Fans posted comments wondering if Dashner’s or Sanderson’s Facebook pages and Twitter feeds had been hacked.)

Mull, who is finishing up an extensive tour for Wild Born, first in a multiplatform series set in a world in which every child has a unique spirit animal, was thrilled with winning a race he didn’t know he had a horse in.

“This is bigger than the time I won a gold medal in a pudding-eating contest,” he said. “It ranks right up there with that.”