Ancalimon has one sister, a twin named Lúthien and a half-brother, King Aragonui of Gondor, who died in the year 2912.
Ancalimon’s father was Arathorn I, father of Aragonui, father of Arador, father of Arathorn II, father of Aragorn II who was known as Elessar.

Ancalimon’s mother was an elf of Imladris named Lutalimë.

Lutalimë was the daughter of Nimloth of Doriath, and so she was the sister of Elwing and the aunt of Elrond and Elros, and the second cousin of Galadriel. Lutalimë was quite old when she met Arathorn I. She was born during the First Age, and thus she was over 2,000 years old when they met. Arathorn was overwelhmed by her beauty and he wedded her.

In the year of 2784 Lutalimë traveled to Mirkwood to visit kinsmen. Whilst she was there she gave birth to twin girls. One was fair, with light chestnut hair and blue eyes, like her mother. That was Luthien. The other was like unto her father, with dark hair and black eyes. Ancalimon. Lutalimë was delighted with her children and she began to trek back to Gondor, but she was attacked by Orcs in the plains of Rohan. Though she had five elven escorts, they did not survive against the onslaught. The Orcs took the babes captive, but within a day the Rohirrim had overtaken them.

They took the babes and when they had looked upon them, one man said, “These children are elven, but not of the same blood. The one is like unto Lúthien Tinuviel and the other is dark like our own people.”

They took the babes to Edoras, where men were selected to take the children to Mirkwood. The two babes were delivered into the care of the King of Mirkwood. Lutalimë had been seclusive while she was there and only a handfew of people had known about the babes. Though it had been but a few weeks, the children had changed, and even those few did not know them. Though no one knew who the two were, they cared for them like their own. When they were 6, it was found out who they were. They loved each other greatly and were glad to know they were sisters. They were quickly taken to Minas Tirith, but Arathorn had already taken a second wife, born a son, and having not known his daughters, refused to acknowledge them as Princesses of Gondor.

When they were 15, they were again taken to Minas Tirith, to learn about Isildur. Whilst they were there, Ancalimon went into a weaponsmith’s shop. At this time, the smith was making a special shield to be branded (not painted) with the White Tree of Gondor. Ancalimon stared at the brand and suddenly one of her gifts was discovered. In her mind’s eye she saw Minas Tirith being over run with Orcs, the White Tree burning, and Aragorn II dying a brutal death. Ancalimon knew this to be foresight, for though they had not spoken of it, Lúthien had it also. Before she could be stopped, Ancalimon took up the brand of the White Tree and she applied it to her hand. Though it hurt and blistered, she cryed out not and did not wince. The weapon smith was astounded by this and he took her before the King Arathorn I. Before the King and all his persons, Ancalimon swore an oath. And this is what she said, “By all the good things of Middle-Earth and Valinor, and Elbereth herself, I pledge that I will do whatsoever it takes to keep those things from happening. Even if it takes my life.” And though she did not know what ‘those things’ were, Lúthien swore the oath as well and she had the mark of a Morgul blade put upon her hand. The King asked what ‘those things’ were, but Ancalimon only replied that she had the gift of foresight and what she saw was for her alone to see.

Soon afterward the two returned to Mirkwood. Luthien, always taking weapons from the Kings armoury. She would go out and search for spiders to fight. Ancalimon joined on most of these trips. They even ventured all the way to the edge of the forest, alone. The met Beor, and though Luthien did not trust him, Ancalimon became quite good friends with him. It was there that she discovered another of her gifts, magic. She was watching the fire and she soundly spoke the elvish words for, “Fire, grow larger!” She had not expected anything to happen, but the fire suddenly shot up until she had to move away from the hearth.She and her sister were mystified.

When the two were 19, Lúthien was sent to Osgiliath, to learn combat, for the elves had seen that she was skilled in this beyond her years. Ancalimon, though, was sent to Lórien, where she was taught lore and the magic of the elves. She was taught by her third cousin, Galadriel, how to use the magic of the mirror. She had a wonderful time, but the two sisters missed each other greatly.

When she was 32, Ancalimon made the dangerous journey over the mountains, to Imladris. She was greated by her older cousin, Elrond. There she continued her studies of ancient history and elven lore. She made the elf-children laugh by preforming bits of magic. She learned a lot there.

When Ancalimon was 45, she traveled back to Minas Tirith. Whilst she was there she met Mithrandir, Gandalf the Gray. She was willing to learn and so he took her as an apprentice. Ancalimon was young and eager and within 18 years she had become Ancalimon the Gray, just like her master. When she turned 64, King Arathorn I, was wounded in battle. As he was dying Ancalimon sent for Lúthien. They went to their father, though he still did not acknowledge them. They watched as their half-brother, Aragonui, was crowned King. They wept bitterly for their father and then they rejoiced at being togethor again.

The two were approached by Aragonui, who acknowledge them as his half-sisters. He gave them great rooms within the Great Halls of Minas Tirith. These rooms were forevermore called the Unknown Royals’ Rooms (it is said that Aragorn II stayed there a few times). Lúthien returned to Osgiliath. Ancalimon stayed with Aragonui and counseled him.

Ancalimon flourished and became Ancalimon the White. Gandalf gave her the ring of Fire, Varnya. She wandered and traveled until the end of the Third Age. She married an Elven Ranger by the name of Anadrion and they crossed to Valinor with the last of the elves.