Why is Petofi helping Quentin?
I think it's because Petofi was a werewolf, too, and knew what it was like. Also, I think Quentin reminded him of himself.
I don't think that's it. Empathy isn't one of Petofi's traits. And we have this exchange from #801/2--
Quentin asks, in a heartbreaking voice, "Why won't you help me? If you know what it's like, why won't you?" To get something, you must pay the price, says Petofi--a little bargaining, perhaps. I'm willing to bargain, says Quentin. You're only willing to cringe, says Petofi, to make inept excuses--you must learn--I paid my price (he holds up his false hand) you must pay yours!
When Petofi first arrived, his primary goal was to retrieve the hand, and Magda had unwittingly made his task easier by having taken it out of her tribe's control. So originally, curing Quentin was a bargaining chip-- something Petofi could dangle before Quentin in exchange for his aid in recovering the hand and at one point to get Quentin to release him (while he occupied Jamison's body) from the locked cell. And bringing Tate in to paint the portrait seemed to set the stage for Petofi to provide the cure down the line.
Petofi claims now that he is helping Quentin because he is part of the future, but Petofi didn't know that until now.
Yes. Now that Petofi and his hand have been reunited, his new goal is to permanently escape the gyspies, so his purpose in aiding Quentin has changed too.
The afghan with the black background is in Tate's cottage, and in exactly the same spot that the Evanses will place it 70 years in the future. Take that, I-Ching!
In the final scene, with Charity threatening to sic her father on Petofi, I wouldn't have known what Petofi did to Charity had he not said "you've lost your voice" because we only had the one camera at that moment and it was trained on the back of her head.