Misconceptions? Misinterpreted?

You ever just stop and try to think of the most possible scenarios that go through your head within a certain time frame and think it's this rational thinking or is this irrational thinking? There are times when I interact with certain people and I think this is a relationship that doesn't feel new but for some reason it feels special? Dating is really more of a strange term to describe something, uncertainty is basically what it is but what if there's more? And I don't mean like "oh the marriage wouldn't have known". I'm talking about is familiarity that was once there but for some reason you can't remember it fully. Either way it makes me think more about whether or not this is the correct action because I've already done it? But I've never been with this person much less strike up a conversation at all. Does it just make it worse to second guess yourself or to just trust in yourself again? Either way I just want to know what anyone thinks of this.