How sure are you that this person/being was remotely watching you? I'm just curious as to how you came to that conclusion.
As for how my vampire first started manifesting himself to me, I'm use to my own spirits' energy and as soon as he started coming to me, it felt as if I was getting an energy upgrade of sorts.
Lots of heavy energy, headaches, muscles twitching - As if my energetic body is humming/vibrating.
Idk how to answer that question tbh. Just as you know your Vampires first started to manifest to you. Something like that

And 'bites' too. Feels like sharp pin pricks, like you'd feel if you were to accidentally prick your finger with a needle.
Haha yep, I have felt those from the first day. When it happened the first time with my first vampire, it kind of offended me, why would anyone bite me I thought o.O Then with some research here at this forum I realized it was common lol.