Eadirin was born at the year 300 of the First Age. Like his father before, he was learning to become a bard. He was studying the arts of Battle-songs and warrior music. Soon he earned a place for himself among the Gatekeepers of the ancient Noldorim city, Gondolin. He was the bard of the Gate of Bronze.
During the assault of the city he fought valiantly against the army of Morgoth. He used his skills as a bard to plant fears into the heart of his enemies, to keep the demonic entities at bay. Together with his comrades he even slew a balrog (though barely survived the encounter). Side by side with his fellow gatekeepers he was trying to protect the city, but in the end there was no hope. As a final command his leader ordered him to leave and tell the tales of those who fought and died at that day.
After the destruction of the city during the First Age, he was among the few survivors who could escape from the death the Great Enemy brought upon his former home. At the end of the era he took part in the last battle against Morgoth Bauglir, though he had an insignificant part to play.
After that, Eadirin was traveling across the lands, living as a wandering bard. He was singing song and telling tales about the Old Times, and Great Kings. His songs were glorious, and almost everyone loved the ancient stories, yet he couldn't hide his own sorrow and grief, and sometimes he unintentionally made his tales darker, which brought pain into the heart of his audience as well. He was living like this, more-or-less peacefully until Sauron appeared in Middle-Earth as the new Dark Lord. Eadirin realized, that the time has come, to wield his sword again, and bring fear and despair into the heart of his enemies with his songs.
He spent much of his time in Eregion, to expand his knowledge and to aid the new generation of bards in their studies. He was a mentor, a teacher from time to time. However he had some other issues on the western part of Middle-Earth, and he was lucky enough to avoid the destruction of Eregion. When he heard the news that Eregion fell he decided to join the army of Gil-Galad, as there was no other way he could help his folk and fight against this new enemy. He took part in the Battle of the Last Alliance. He witnessed the fall of his King, Elendil the Tall and the destruction of Sauron. After that he disappeared again. He returned to his previous life form: wandering around, singing songs about the Old Times, heroes, Kings, adventures. He was spending his life during the Third Age until he heard: Sauron has returned again. Now, the time has come again to draw his sword and sing his songs again, and to aid the people of Middle-Earth, one last time. But how his own tale will end, noone knows.