The decision to make Euron a little more charming (even if slimily so) is a big change from the books where he rapes and pillages his way around. He captains a ship called Silence, named for the fact that he cuts out the tongues of all who board. In the book A Feast For Crows, like in the show, he returns to the Iron Islands, kills his brother, and claims the throne. He also wishes to court Daenerys, but sends a crew to do so in his name — which is like the ultimate in laziness. He knows she has dragons and foolishly thinks he will be able to control them with his dragon horn.