"My brother currently has more important things to worry about than Valyrians conquering Westeros", Brandon Snow, king Torrhen's bastard brother, left behind as castellan for Winterfell, stated, "he isn't here. If you really want him to bend the knee, either wait a year or two, or go north to meet him, either way, I am not the king or even a prince, me kneeling wouldn't mean anything. Alys, go and fetch a map of the Greater North."
"I will dad", Brandon's daughter replied, running to the solar.
"What do you know about the Night's Watch?" Brandon asked Visenya Targaryen.
"They are a thousands year old organization keeping watch on a wall of ice", Visenya replied, "supposedly to defend against a race known as the Others."
"There is nothing supposedly about it", Brandon countered, "although I admit, the Wall hasn't seen any in over 6000 years. In truth, the Wall is merely maintained in case the enemy would be able to get past the siege. Something they haven't managed to accomplish in the last 3000 years."
Brandon rolled out the map, "as you see, here is Moat Cailin, here Winterfell, then there is the Wall." Brandon now moved his finger much farther northwards until he reached the lands of Eternal Winter, "here is the last Stronghold of the Others. Around it is the double-walled city of Longsiege. One wall surrounding the Stronghold, one to defend the city from outside attacks. Nine moons back, we received news that the Others were moving and that Governor Greystark expected them to make a renewed attempt to break out. In response, my brother rode out with most of the Armies of Winter to reinforce Longsiege. Should you go there, keep your dragon away from the Others' stronghold, I don't want to risk it getting killed and resurrected as a wight, regular wights are bad enough. You can take the map with you, we have others."
When Visenya returned to Aegon several moons later, she refused to speak of what she had seen in the far North to anyone else than her siblings. Neither Targaryen would ever explain what Visenya had said, but the Targaryens decided not to conquer the North. They also ensured that regular shipments of grain and steel were sent northwards to the Night's Watch, along with as much dragonglass as their people could mine in Dragonstone.
When the Ironborn had decided to make use of the Armies of Winter being in the far North, Visenya had personally flown off on Vhagar to wipe out the Ironborn.