Dreaming of a stranger can have two totally opposite meanings. The first is the obvious fear of the unknown, of not recognizing whom you are interacting with. The strangers are, as they sound, strange to you. You know nothing about them and nothing of their intentions. Thus, this is a sign that you are wary in case something happens.
However, it can also signify an interest in the unknown. Once again, you know nothing about whom you dream about, yet there is that mystical sense of being intrigued about things and people you do not know. Curiosity at it’s best.