The Lady

The Lady is a woman who appears late in the game. She appears to be a sacrifice set up for a tribe of gnomes in order to appease their god. The brothers decide to rescue her, and in return she seemingly guides them towards the Tree of Life.

Physical Appearance
The Lady appears to be about Older Brother's age. She wears a dress with a brown and orange top section and a reddish skirt. Her black hair is tied into a long ponytail.

When she reveals herself to be a spider lady, her torso and skirt is replaced by that of a spider's abdomen. Her hair is also tied up into a bun.
 * Spoilers*

Personality
The Lady, after rescued, is willing to help the brothers by acting as a guide through the frozen city. Interacting with her at certain points shows her flirting with Older Brother.

This unfortunately acts as his foil when she tricks both brothers into walking right into her lair, even when Younger Brother is suspicious. There, it is revealed she is a Spider Lady who was most likely intent on eating the two. Once all her legs are pulled, she manages to fatally stab Older Brother, effectively taking him down with her before she died.
 * Spoilers*

Trivia
-Some concept art shows her hair tied up in two loops, pale skin, and glowing eyes.

-Her true identity/form is foreshadowed by all the superhuman jumps and feats she makes during the frozen city portion of the game.

-When most of her legs are pulled off, it actually looks like she's trying to ESCAPE from the brothers, rather than continue fighting them.

-It's likely that the people wrapped up in the cave right before her lair are also people who tried to find the Tree of Life and its water. It's also possible that she charmed them into her trap much like she did to the brothers.