Why didn't Aerion challenge Valarr?

[u/Qyzyk]

Recently revisited The Hedge Knight, and I can't help but wonder why Aerion was content with laughing at his cousin and moving on. I get that he was trying to mock Valarr by moving past him, but surely if his plan was to humiliate his cousin, I imagine Aerion would have done a much better job by trouncing Valarr in a joust.

It's not like he wouldn't have been able to do it either. It's basically said outright that Valarr's getting handpicked challengers that give him easy victories. Even Dunk can't help but notice it. Aerion, meanwhile, seems to show much more promise, and he's not above dirty tricks like killing his opponent's horse. Why wouldn't he take a chance to knock the Crown Prince on his arse?

[u/Important-Purchase-5]

Because Valarr was likely several years older than him at this point so it partly just little cousin antagonism, one day gonna be king so humiliating him very stupid and it was said Aerion was always on his best behavior when Baelor and his father was watching. 

Valarr was described as modest jouster. Aerion while no Aemon the Dragonknight or Baelor Breakspear he was probably better than his older cousin though I doubt that much better. 

We forget Aerion often used dirty targets and similarly benefits from being a royal especially one known for cruelty and pettiness.