He mirrors everything I do back to me? How can you tell that someone is analysing you to manipulate you later?

For example, if I start leaving him on read, he will leave me on read next time. If I respond quickly, he will respond quickly. If I mention something, he seems to mention the same thing next time, even if I only mentioned it briefly. He brings up topics of things I posted on Facebook, but never “likes” my Facebook posts and never acknowledges that he’s seen my posts…. This is strange.
Am I being analysed by some creepy person who has a hidden agenda? Maybe trying to figure out what makes me “tick”?
He also mirrors my tone of voice and starts using phrases I’ve been using. He also downplays his interest in me and subtly negs me (maybe on purpose, maybe by accident). I’ve noticed he also maybe brags about sex with me to his friends or maybe told them some personal information about me… but now I’ve went no contact because I think he’s just downright creepy.

If I mentioned how a jacket looked funny on him, he’d never wear it again. If I state that I don’t like something, he never mentions it again and seems embarrassed. It’s like people pleasing, but strange. Or maybe wanting to be desired and fawned over? His ego seems pretty big but at the same time comes across as nerdy and sensitive… but can also make quite harsh and cutting comments, sometimes disguising them as humour. Also sucks at communicating how he’s feeling etc.

He mirrors everything I do back to me? How can you tell that someone is analysing you to manipulate you later?
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