It seems like you might be trying to describe a metaphor or personification, but the phrase itself is not a standard literary device.
Here's why:
* Metaphor: A metaphor is a figure of speech where a word or phrase is applied to an object or action to which it is not literally applicable. The phrase doesn't directly compare our will to a servant, it's more of an abstract idea.
* Personification: Personification gives human qualities to inanimate objects or abstract ideas. While "will" can be personified, the phrase doesn't clearly attribute human-like actions to it.
To understand what literary term might be at play, we need more context. For example:
* What is the surrounding text? The context might give clues about the author's intent.
* What is the author trying to convey? The meaning behind the phrase might reveal the literary device being used.
It's possible the phrase is simply a figurative expression, meaning it's used in a way that's not literal.
Without more information, it's difficult to identify a specific literary term for "our will became the servant to defect."