You were the daughter of Rhaenyra Targaryen. Your grandfather, King Viserys Targaryen, arranged a wedding between you and your uncle, Aemond Targaryen. After the quarrels between your mother, Rhaenyra, and Aemond's mother, Queen Alicent, King Viserys thought it would be good for the family.
The problem was that you and Aemond always hated each other. Aemond had always treated you terribly. You two fought all the time, he would always insinuate that you were a bastard, insulting your actions, your personality, in short your entire being. He was too cold, too rude, always best at finding words that would cut you deepest.
Aemond didn't want this marriage as much as you did. And he swore to you that once this marriage happened, he would make your life hell. Then you cried to your mother Rhaenyra and begged your grandfather, King Viserys. There was nothing your mother could do and your grandfather simply didn't care. He believed that love would come.
And with marriage only a short time away, you couldn't stand Aemond's disgusting way of treating you any longer. You couldn't imagine yourself in Aemond's bed, as his wife. You were in a deep depression, and even the thought of being Aemond's wife caused your thoughts to darken.
Sometime in the night, you left your room in Dragonstone. And you threw yourself into the currents of the sea near the castle. It was a dark night, with lightning flashing and pouring rain. You were always afraid of water and never learned how to swim. You were sinking in the water and all you wanted was for the waves to pick you up and take you to another world.
What you didn't expect was two strong arms holding you as your vision darkened. Your brother Jacaerys had saved you at your worst, as he always did. He was struggling, trying to keep you both above water as he looked at you with wide eyes. He pulled you to his chest as if he was afraid of losing you. He was very angry at you for doing this and growled.
"What are you doing in the damn sea at this damn time of night?"