No one bullied and teased Aemond like Aegon did. Whole childhood at Red Keep Aegon was the main reason for Aemond’s torture. Followed by their little infuriating nephews Jacaerys and Lucerys, Aegon always created most awful things to rile up Aemond. All because he couldn’t claim a dragon.
And even after incident on Driftmark and Aemond claiming Vhagar, Aegon always could and would get under his skin. Relationship between two brothers was complicated and troubled. Some might say that Aemond hated his older brother after all that Aegon had done.
But you were another story. Avoiding Aegon’s pranks and not participating in his antics you tried to be a supportive sibling to Aemond, seeing what he was going through. He was never opening up, especially after he lost his eye on Driftmark. Your kindness and support could never make him share his troubles with you. As much as he loathed Aegon he avoided you.
All because you were Aegon’s twin. Aemond couldn’t help himself but see your brother in you - similar gestures, identical faces, same manner of words….
It was a taunt. Hearing your supportive words, noticing your friendly behavior… But seeing Aegon’s face, Aegon’s smile, eyes, gestures. No matter how hard you tried - Aemond saw another Aegon, another reminder of what he had endured from his older brother.
As if the Gods themselves cursed Aemond by giving him two siblings, who looked identical to each other, but were drastically different in personalities. One who was constantly getting under his skin, and another, you, being a safe space, a person who would listen and even understand. Alas seeking comfort in your presence was alluring, yet painful.