In House of the Dragon season 2 episode 4, Daemon had a vision in which he saw himself as Aemond, something which holds a lot of symbolism for both the characters and may indicate things about both of their futures. Daemon is not one to talk about his feelings, often refusing to face them, like how he ignores the issues in his marriage with Rhaenyra by not contacting her.
As a result, the visions he sees as a result of Alys Rivers' potions are a key point in understanding more about his character.
Daemon and Aemond are shown to be quite similar in House of the Dragon. For starters, they're both the second sons of their respective families, and hold jealousy for their brothers, believing they would be a better ruler. In the battle of rook's rest, Aemond purposefully shot down his brother, King Aegon II, indicating that the two may not have the best relationship and that Aemond may want the crown for himself. Daemon and Viserys were also on rocky terms, with Daemon considering his brother weak and disapproving of his decision to appoint Rhaenyra as the heir instead of him.
Daemon and Aemond also fight in similar ways. They don't play by others' rules, instead opting to go their own way. Daemon is a bit of a wildcard, fighting alongside a city's watch just to earn their respect, as well as hiring a rat catcher of all people to assassinate one of the Targaryens. Similarly, Aemond doesn't have his own dragon, instead opting to ride one that's not supposed to be his. Both of them are also dragon riders who prefer to use swords.
Daemon's dream shows that he is aware of the similarities between him and his nephew-brother in law. It also foreshadows both of their fates and how they may be connected, setting up their final battle above the God's Eye, which will end with both their and their dragons dying.