I think Tyrion is anxious because he's heard that Dany has disappeared and realized that Barristan is currently leading in her stead. Barristan certainly didn't like the dwarf with his dishonourable cunning ways but after Cersei's dismissal of him he surely has a thing against Lannisters.If he had been brought before Dany he could have argued that he used his cunning to help in her war effort (despite most of the credit going to Victarion), and added his knowledge of dragons as a bargaining chip. The fact he killed his own father might not please Barristan but it will surely prove to Dany that he's pretty much emancipated himself from his family. And the obvious thing is that he is currently on a battlefield, which so far has proven not to be his favorite spot. And if you want to make him really miserable you give Penny the pale mare. Tyrion might have hardened himself enough to kill his father but he's not yet heartless. I think it's pretty obvious when it comes to Victarion. Once the battle is won everyone will applaud his intervention but when Dany comes back she'll be grateful but not enough that she'll agree to marry him. Victarion will be furious and eventually try to use the horn then it's anyone's guess, but I don't think he can control a dragon. Meereen and the entirety of Slaver's Bay will still be devastated and Dany will realize she no longer has a kingdom but only the remnant of a remnant of a kingdom. She'll use Victarions ships to go back to Westeros with her unsullied, Dothraki and the rest of her followers. I can't tell if it will happen before or after Victarion tries to betray her out of bitterness.