Most of the time, when reading a book or watching a movie or TV show, the story ends where it does and the characters' journeys come to a close. The audience doesn't often get to see what happens to the characters after the main story ends because the creators obviously don't usually expand the story past its natural stopping point. Luckily for Tolkien fans, however, J.R.R. Tolkien did a lot of writing about what happened to some of the characters after the events of Lord of the Rings. His world of Middle Earth was so expansive that even the character's stories were extended.
One of these characters, who really functions as one of the main protagonists of The Lord of the Rings, is Aragorn. In the story, the audience meets him as a ranger and sees him develop as a leader, finally taking on his birthright as King of Gondor. In the movies, the last that is seen of him is at his coronation, but of course this isn't actually where his story ends. What happened to Aragorn after the conclusion of The Return of the King, and how did he lead Gondor through this new era of peace?
Aragorn first entered the story of Lord of the Rings as a Ranger named Strider, and he aided the Hobbits on their journey and took them to Rivendell. He became a member of the Fellowship of the Ring and travelled with the Hobbits and their other companions on the way to Mordor. They are forced to go their separate ways part way through the journey, and Aragorn fought against Sauron's armies from Rohan and Gondor while Frodo and Sam make their way to Mount Doom. He led the Army of the Dead to defend Minas Tirith during the Battle of Pelennor Fields, and led the Army of the West in the final battle against Sauron's forces at the Battle of the Black Gate.
Following the defeat of Sauron, Aragorn led the charge against the remaining Orcs in Mordor and, together with his army, wiped them out — freeing the residents of Núrn (who were enslaved to Sauron) in the process. After all of the fighting was over, he was finally allowed to be crowned King of Gondor, named King Elessar because that was the name of the Elfstone he wore. Aragorn was the twenty-sixth King of Arnor and the thirty-fifth King of Gondor, making him the first High King of the Reunited Kingdom.
His reign brought a period of great prosperity to these nations, partially due to the post-war rebuilding campaigns that he championed. He also ensured to foster good communication between the different peoples of Middle-earth, and there was a renewal of cooperation amongst Men, Elves, and Dwarves. He worked to try and bring the land back to its former state after being decimated by Sauron and his war for so long. He was able to bring Gondor back to its former glory after years of losing land and power, but the unification he brought about was just as important. After all of the war that Middle Earth had endured, peace was the top priority, and Aragorn managed to unify much of the lands that remained.
All of the accolades are great, but Aragorn got his true happy ending by marrying Arwen not long after this, and they ruled over Gondor and Arnor together until 120 of the Fourth Age. They had a son, Eldarion, as well as an unspecified number of daughters, who all remain unnamed. At the end of his life, Aragorn could sense that his time was drawing near. He said goodbye to his children and left his crown and scepter to Eldarion to rule in his stead, and departed for the House of Kings in Minas Tirith.
Also referred to as Rath Dínen (which is Sindarin for "Silent Street"), this was where the tombs of past rulers of Gondor were found, and where the rulers themselves were laid to rest. Merry and Pippin were actually honored with tombs here when they passed, having spent the final years of their lives in Gondor with Aragorn. Aragorn took himself to the House of Kings, which became his final resting place. Arwen stayed at his side until he passed, his soul leaving the mortal realm to go to a place that even the wisest had no knowledge of, and leaving behind a great legacy in his wake.
Arwen, of course, had chosen a mortal life to stay with Aragorn rather than accompanying the Elves to the Undying Lands, and she was never the same after her husband's death. The grief of his passing weighed heavily on her, and she went to stay in Lothlórien for a while. A year after Aragorn's death, Arwen died of a broken heart in Lothlórien. When both of his parents had left this mortal realm, Eldarion finally began his reign and ruled as the Second King of the Reunited Kingdom for many generations to come.