Hope for Undomiel.

[Legolas]

At what time did she actually turn from elf to human? I thought that it was Elrond's choice, and that his choice would be the same one for his siblings. Meaning that Arwen was an elf, and she did not have that choice, since she was the daugther of 2 elves.

Arwen was not an elf. She was never an elf. She wasn't an elf who "became" human. She was a half-elf who had not made her choice, and then she was a half-elf that was to share the mortal fate of man. Tolkien is explicit about this in his letters.

Elrond too was not an elf. He was an half-elf who would share the immortal fate of the elves.

Elrond's children got the choice because they had a renewed elvish strain from their mother, Celebrian. They were not the children of two elves, but rather one half-elf and one elf, making them half-elven too.

Like I recommended in my initial post: Read the article I linked to.

I mean, JRRT tells us that Galadriel was mighty among the Eldar so couldn't The Lady have found a way to supersede the choice of Arwen?

No. Immortality/mortality could only be changed by Eru himself. Eru gave Earendil's family their choice, and it was only he who could alter one's fate.

[ March 26, 2003: Message edited by: Legolas ]