how does daemon targaryen die ?

House of Dragon has yet to reveal the fate of Daemon Targaryen. However, according to the book "Fire & Blood" storyline, While searching for Aemond and Vhagar, Daemon kept Nettles, a 17-year-old dragonseed, by his side in Maidenpool. After learning from Mysaria that Nettles shared Daemon's bed, Rhaenyra sent word to Lord Manfryd Mooton that Nettles should be killed.

Manfryd was reluctant to carry out the order. As Norren showed the letter to Daemon, he thanked the maester for his warning, and a tearful Nettles was allowed to safely depart on Sheepstealer the following morning. Also, on the same day, Daemon announced that he was leaving for Harrenhal.

As squatters fled from Harrenhal when Daemon arrived on Caraxes, the prince stayed in solitude to wait for Aemond. Thirteen days after Daemon had waited for Aemond, Aemond and his paramour, Alys Rivers, arrived on Vhagar. As the two dragons grappled in the Battle Above the God's Eye, Daemon leapt off his saddle and drove Dark Sister into Aemond's blind eye.

Caraxes crawled to the shore before dying. The bodies of Aemond and Vhagar were discovered at the bottom of the lake years later. Daemon's body has not been found, but historians believe he died there as well.