彼の元で護衛を務める。
Does it mean "for", "on behalf of", "in the name of"? Or "under the guidance of"?
What's the difference between that and の下で?
Can I replace で with に?
彼の元で護衛を務める。
Does it mean "for", "on behalf of", "in the name of"? Or "under the guidance of"?
What's the difference between that and の下で?
Can I replace で with に?
I think it is using a wrong kanji, strictly speaking.
彼の下{もと}で護衛を務める could mean (1) to work as a guard for him or (2) to work as a guard under him ("he" is also a guard). To me, 彼の下{した}で makes the interpretation (2) more likely.
Regarding the particle, here 務める means a state rather than a movement, so で is much more natural. 下に works better for action like 彼の下に集まる (gather around him as a leader). Also, a phrase like 法の下に平等である (equal under the law) is natural despite its being a state, but this kind of に should be only for written/strained expressions.