- "I came thus far with my six fellows, loved a girl of the islands, and felt I had had enough of the sea. And there was no point in returning to Narnia while your Majesty's uncle held the reins. So I married and have lived here ever since."
- ―Bern [src]
Bern and six other Lords were sent to "explore the seas beyond the Lone Islands" by King Miraz, in an attempt by him to be rid of them. Lord Bern remained behind at the Lone Islands, while his companions continued on toward the eastern end of the world. He bought slaves from the slave trader, Pug and freed them, possibly in repentance for his early abandonment of his friends.
King Caspian X, during his famed journey over the eastern seas, was purchased as a slave by Lord Bern, after being captured by slave traders before any of the island dwellers were aware of his true identity.
Bern bought the king because he reminded him of Caspian IX, the father of Caspian X, whom the Narnian lord had served prior to the king's death, and his exile by Miraz. King Caspian revealed his identity to Lord Bern, who then assisted the king in reestablishing a Narnian presence on the islands. Upon his departure, Caspian threw out the present, corrupt governor, and made Lord Bern the Duke of the Lone Islands, as he had "had enough of governors".
In the film adaption, Miraz had tried to kill Bern and the other 6 lords, after assassinating his brother, so they fled to the Lone Islands. It was there that they learned of a mysterious Green Mist that had been sighted in the East, where numerous people were apparently being taken by it. The 7 lords made a pact to find the source of the Mist, and destroy it.
Each of them set sail, but, unfortunately, before Bern could leave, he was captured by the corrupt government in Narrowhaven, and was imprisoned in a jail-cell, where he must have remained ever since. He spent several years there, before Caspian and the Dawn Treader liberated him. The rest of the lords had by then long since left, to continue their quest for the Mist.
Bern had with him an old Narnian sword, originally from the Golden Age of Narnia, which he had kept hidden in a cave for years. It was one of Seven Swords, originally a gift from Aslan to Narnia, to protect it in times of danger. It had been given to him by Caspian IX, though how he got it is unknown.
- Lord Bern's name probably stems from the Old English word "berne", which means "warrior": a classification that fits Lord Bern as a participant in the re-conquest of the Lone Isles.
- It can be assumed that when the Dawn Treader left Narrowhaven, in the film, Caspian left Bern as its new Duke, to rule over it wisely and justly, as he did in the book.