There is no positive or ethical 'foot slave' concept in a proper story. However, in a fictional world, perhaps a dark elf might be in a situation where they are forced to serve due to a cruel curse or an evil master. But this should be seen as a wrong and unjust situation that needs to be changed.
One common theme could be oppression. The dark elf is in a position of servitude which is unjust. Another theme might be the struggle for freedom. They constantly strive to break free from their degrading role. And also, there could be a theme of hidden strength. Despite being in a lowly position, they possess some inner power or ability that can eventually lead to their liberation.
One interesting plot could be a dark elf slave who discovers hidden magic within themselves that is unique to their kind. This newfound power might help them in their struggle against the unjust treatment they receive in the wizarding world.
Some characters might start as meek slaves but develop into strong - willed individuals. For example, a dark elf slave could initially be submissive due to fear but gradually gain confidence as they face different situations and make new friends.
One alternative topic could be the dark elf's unique weaponry. For example, their use of poisoned daggers or enchanted bows. These weapons are often crafted with great skill and are an important part of their combat abilities.
The dark elf may be lonely. Living in a world separate from humans, she sees the man as an interesting specimen. Capturing him gives her the chance to interact with someone different, to learn about a new culture and way of life, even if her methods are rather extreme.
One common theme is the struggle for freedom. Elves, being slaves, often strive to break free from their bondage. Another theme could be discrimination, as they are slaves and likely face unfair treatment from other races. Power imbalances also play a role, with the masters having power over the elf slaves.
This kind of novel plot is more common. You can refer to the following similar novels:
Lord of the Dark Forest: The elf who transmigrated into the novel has the genes of a dark elf and a nature elf, so he has unique abilities and characteristics. The relationship between the Dark Elves was a complicated triangle.
A dark elf teen usually has pale skin, which is almost like moonlight in the dark forest. Their hair is often black as the night sky, and it can be long and flowing or short and spiky. Their eyes are a distinct shade of purple or deep blue, like the rarest of jewels. They are slender in build, with a grace that comes from living among the trees and shadows.