Then again, maybe Tyrion is just good with dragons and Dany’s kids understand that he doesn’t mean them any harm.
Given all the clues that have been dropped in the show and in the books, Tyrion could easily be revealed as a third Targaryen.
Maybe they just have a good feeling about Tyrion.
He doesn’t have to be another secret Targaryen to necessarily get along with Rhaegal and Viserion; dragons are magical creatures that can apparently sense Jon’s status as a Targaryen when even Jon himself is unaware.