Here is a 30min interview of Rick Riordan Blood of Olympus.

I didn't know Blackjack wad a mere and then a stallion, I always thought he was a stallion. Lol, Uncle Rick said:well you know Percy is not very observant and also I forgot.(lol!)

There was another interview I watched that a fan was like: If you were too change one thing in the movies, what would it be?
Rick Riordan was like: only one?

I agree when he said why there was no Anabeth or Percy pov.