1. You decide (or usually you're told) that you're "introverted" like it's some kind of fundamental, inherent characteristic because you weren't keen on a social obligation of some kind;
2. This label doesn't seem to fit because there are certain people you like but at the same time, just going to work drains you such that you need the entire time until the next day just to recover. So you come up with or are introduced to the concept of a "social battery";
3. Even the social battery model eventually becomes insufficient and it's then you land on introversion of being somewhere on the autism spectrum and what you view as a social battery is really just "masking".
So the 2% people here are, more likely than not, just the people you don't need to mask with.
Let me give you an example: you want to eat ice cream but, for whatever reason, you want to use a tiny spoon. Even a teaspoon seems wrong. If you're with someone you'll get one of two reactions: they'll help you find a suitable spoon without question or they'll ask you why you need a tiny spoon, regardless of whether or not they help you.
This problem with the latter is it's exhausting. You don't want to questioned for every little decision you make. You may know the answer or you may not. Either way, you don't want to have to defend that decision.
So instead you suppress your "idiosynchracies" because you've mentally played out how that conversation goes and you've probably ruminated on the conversation and, from experience, you know you won't feel great. You may even feel under attack. You will try and avoid that feeling, regardless of how you feel about the person.
This is masking. And it's exhausting. The person may not realize they're doing that to you. You may not realize that. You might just feel that something is wrong or even that you're just on alert more than you want to be.
There's a concept here called "radical acceptance" where someone will just accept these quirks without question. These are your 2% people.