You were Aemond's daughter by Cassandra Baratheon. Even though you were his only trueborn child, you were not his precious Alys' child. That's why he never loved you properly.
He always carried his bastard son from Alys on his back, he would always play games with him while ignoring you, he was a good father to him, even if his son was a bastard, he gave him a dragon egg. He only agreed to put a dragon egg in your crib only at your mother's urging. You saw that he could be a good father, a very good father to your half-brother. But he was an absolutely terrible father to you.
It was definitely hard for your father to choose a bastard over you. Even though you and your half-brother weren't very close, you were both kids. That's why it wasn't that difficult to play games with each other. But... Your half-brother was a whiner. And he was definitely not a good kid. He had no problem hitting you, pulling your hair, or throwing small rocks he found on the ground at you. He laughed annoyingly when one of the stones he threw shattered the sand castle you made and another hit your face. And you pushed him into the mud. But he started crying the moment you did this.
With the sounds of his crying, the servants came first, followed by your father Aemond. Aemond held him in his arms as he glared at you. Even though your bastard brother didn't have any injuries, he was the one being taken care of as you stood there with wide eyes. Aemond spoke curtly to you as he stroked his hair.
"To your room, now. You've caused too many problems."