(Spoilers Extended) Tyrion will drive Victarion insane
Tyrion is repeatedly associated with monkeys. He tells Young Griff
> Your false father is a great lord, and I am just some twisted little monkey man.
Recalling Tywin
> Lord Tywin was not pleased. "The gods made you a dwarf. Must you be a fool as well? You were born a lion, not a monkey."
And the preacher in King's Landing says
> We have become swollen, bloated, foul. Brother couples with sister in the bed of kings, and the fruit of their incest capers in his palace to the piping of a twisted little monkey demon.
Meanwhile, Victarion absolutely despises monkeys during his voyage
> The monkeys, though … the monkeys were a plague. Victarion had forbidden his men to bring any of the demonic creatures aboard ship, yet somehow half his fleet was now infested with them, even his own Iron Victory. He could see some now, swinging from spar to spar and ship to ship. Would that I had a crossbow.
Maybe a Tywin-Tyrion reference there at the end
Then there's this passage, where Victarion connects mockery and laughter directly to monkeys
> Victarion Greyjoy mistrusted laughter. The sound of it always left him with the uneasy feeling that he was the butt of some jape he did not understand. Euron Crow's Eye had oft made mock of him when they were boys. So had Aeron, before he had become the Damphair. Their mockery oft came disguised as praise, and sometimes Victarion had not even realized he was being mocked. Not until he heard the laughter. Then came the anger, boiling up in the back of his throat until he was like to choke upon the taste. That was how he felt about the monkeys. Their antics never brought so much as a smile to the captain's face, though his crew would roar and hoot and whistle.
With Tyrion and Victarion together in Meereen, I think George is going to have an incredible amount of fun with their dynamic