There are people — surely not you — after whom every interaction leaves you feeling like someone drank your energy through a straw.
And you start noticing it happens at every single meeting.
And once you notice — you start keeping your distance.
Online you meet him (or her) everywhere. He pleads for attention. He begs you to notice how wonderful or attractive he is. She requests, every five minutes, validation for her suffering or an empathic hug.
And the thing is — it works for them, the emotional blackmailers. At least in the short term.