The Vision
Elrond called his sons, Elladan and Elrohir, into his study. "The boy Chieftan of the Dunedain arrived last night, as you know, for fosterage during the regency. There are two things he must not be told. I will make a general announcement about this later, but I wanted to speak to you two privately, because I wanted to tell you about my vision. Firstly, he will be known as Estel, and will not be told his true name and lineage until his majority. This is to protect him, and all in Imladris already understand the reasoning. The second, and this may prove difficult for all of us, is that he must not be told that he has a foster sister. No one is to mention Arwen."
"But father," objected the twins in unison.
Elrond held up his hand. "I have had a vision. Of the two of them, together. They were standing under mallorn trees, so they must have been in Lothlorien. Arwen said she would choose mortality, to stay with him."
"No!" exclaimed Elladan.
"It must never be," Elrond said. "I would not lose any of you. I have sent word to Arwen that she must remain in Lorien for the next score years. I have not told her about the vision. She has always been of the opinion that attempting to circumvent fate always brings it about. However, I do not believe that is so. I cannot. Arwen and Aragorn must not come to love each other as brother and sister. There must be no bond between them."
"We understand, father," said Elrohir. "We will say no word of her."