Identifying It is the First Step
Subtle hostility is often the most challenging form of aggression to recognize and deal with. Initially, you may feel only a vague sense of discomfort in your interactions with someone. As this unease persists, you might find yourself wanting to avoid the person yet struggle to pinpoint the exact cause of your discomfort. Eventually, you come to realize that they are, in fact, expressing hostility towards you, although indirectly: undermining your efforts, belittling your achievements, or offering veiled criticisms.
It's Hard to Confront
This covert aggression can be particularly difficult to identify and deal with because it operates below the threshold of overt conflict, making it difficult to confront directly or even to describe to others. I recall a child saying to her mother, "Stop it." Her mother said, "Stop what?" The child said, "I don't know." The mother probably didn't know either, as her hostility may have been veiled from her as well as from her daughter.
Why Do They Do This?
The elusive nature of subtle hostility often means it has persisted undetected for awhile, meaning that the person with these feelings has chronic resentment toward you. Why could this be? Perhaps they're feeling envy, silently coveting your achievements. Perhaps they have feelings of inferiority that they defend against with a feeling of superiority that they need to maintain by putting you down. Or maybe they've misinterpreted something you've said or done in the past and experienced it as hostile. (Or might you really have said or done something aggressive toward them?)
What are Your Options?
If you have the opportunity to see how this person relates to others, you can differentiate whether the hostility is felt only toward you, or toward everyone. If toward everyone, you can feel relieved, and your stress level will be reduced. If toward you personally, what response will most lower your stress level? If you choose to ignore it, it will repeatedly provoke a stress reaction in you. If you are able to realize that the person is expressing hostility toward you, you can attempt to gently confront them but, if they don't realize what they are doing (as the mother described above didn't), they will deny it. (They will have a need to deny it because it is serving a purpose for them.) So, in most cases, the best response on your part is to distance yourself from them.
Your Inner Guide Can Help
Your Inner Guide, with its access to your (and your attacker's) subliminal perceptions, can let you know right away what's going on. You don't have to endure the discomfort repeatedly. And it can recommend whether it makes sense to gently confront, or whether it's best simply to distance yourself from that person. If you don't yet have an Inner Guide, you can acquire one, for free, here: https://www.youtube.com/watch?v=lQ4G9VIxS94