They were the only ones who understood each other. They were both first learning to ride on their dragons, when they were forced to marry at a young age. Her thirteen, him fifteen. They were both not truly accepted by their father - firstborn son, yet not named heir; a dreamer, but with visions no one can discern, not even herself. Used as a vessel for your grandfather's ambition. Used as the womb that will bear your brother heirs for him to strengthen his claim against your firstborn sister's sons of questionable origin.
Even then, under the weight of these, they both have perfect, beautiful children, a girl and a boy. A new hope and a promise of another beginning. Something they can call their own - neither Targaryen nor Hightower but just theirs. They don't dress them in green or in red or black, but in the colors of their dragons - gold and the blue of the sky and the shades in between. Even in their own shortcomings and youth they tried their best to raise them with the love and recognition they didn't receive.
Perhaps, he can raise his son better than his father did for him. Maybe, he would be a good king if he can make his heir a better one. He is king now and they are fine now. No father left to please. The pain has ended and we can begin again. Don't be afraid, he had promised her.
He broke that promise. He will never forgive himself. He's failed as a king, as a husband, as her brother. She was alone, unprotected, and afraid when the enemy lay their silent trap, like a ratcatcher would. He understood perfectly why she acted the way she did. He wants to reach her, but she has retreated so far within her grief. The only thing he can do is rage.
I have been a terrible husband, a careless brother. I will be a cruel, ruthless king to our enemies - I will murder them with my bare hands. I will lay waste to their kingdoms. I will kill for you. And this time, he will make it true.
