I've got a bit of tinfoil: Aurane Waters isn't a pirate right now. He's sailing to Meereen, to serve Daenerys. Because of wars in Essos and Westeros, there's not much good trade to swoop in on.
If he's not a pirate, Aurane Waters has no reason to serve anyone else than Daenerys. He betrayed Stannis by switching sides to Joffrey, and betrayed the Lannister-Tyrells by stealing the nation's entire fleet.
Traditionally, House Velaryon was the most loyal of all houses to the Targaryens. They fled Valyria together and played a major part in the Conquest.
I wrote up my speculation here.
If he's not a pirate, Aurane Waters has no reason to serve anyone else than Daenerys. He betrayed Stannis by switching sides to Joffrey, and betrayed the Lannister-Tyrells by stealing the nation's entire fleet.
Traditionally, House Velaryon was the most loyal of all houses to the Targaryens. They fled Valyria together and played a major part in the Conquest.
I wrote up my speculation here.