The narcissist doesn't need to hear you tell them things in order for them to know it about you.
You can keep so much to yourself, but in the way you react, respond, present? Those are all telltale signs of how you've been treated, what you're like as a person, and how you love, trust, and make decisions.
Not telling anyone things about you doesn't mean toxic, controlling people won't learn it all about you eventually.
Here is how narcissists gather that skill, and what the skill actually is.

1From the first day, the narcissist's eyes were peeled

When you first met the narcissist, you were standing before them, thinking about getting to know them, and from that early point, the narcissist was already studying you.
You might think, "What could they possibly be studying about me at that early stage?"
You'd be so surprised.
Narcissists are looking at the way you tense up when someone around you unexpectedly raises their voice. They're watching the way you laugh a little too hard if you're feeling a bit nervous. They're looking at how quiet you go when you feel as though you're being criticized.
It's the same old story of you assuming that you're getting to know someone new and harmless, while they're building some kind of toxic file about you and everything that you are.
It's the weirdest thing to those who are far from narcissistic, because we don't have those kinds of motives when we meet new people. We're just interested and excited to get to know someone, but that can never be said for the narcissist.
When you have those unguarded moments where a flash of discomfort enters your body or mind, the narcissist wants to take notes and remember it for next time.
See alsoThe Narcissist Starts the Fight in the Car So You Walk In Broken While They Walk In Smiling
They aren't bothered by who you are, they just want to know things about you they can use at a later date.
2The questions they asked were never the questions you thought they were

- "What kind of childhood did you have?"
- "Do you have any major regrets?"
- "Do you wish people understood a certain aspect about you the most?"
When you're being asked these questions by someone who is trying their best to show you that you've got a connection, you're being asked to surrender some of the most personal details about your life.
Naturally, those questions will be dressed up with intrigue, a smile, a nod, a sympathetic pat on your shoulder. You really feel as though they're listening to you, but I'm here to tell you the truth about what's going on.
You feel like you're in the midst of an intimate discussion, so it's easy to assume that opening up is the right thing to do.
It's not.
See also5 Passive Aggressive Tactics Narcissists Use That You'd Never Recognize As Abuse
You feel safe because you were hooked, and because it feels as though nobody has paid this much attention to you before.
The answers you gave all act like singular keys that unlock your emotional doors. The narcissist picks them up as you drop them, and waits for the moment they need to use them all over again.
Triggers, fears, insecurities, regrets, loves, hates; everything you say will be used against you.
3Everything you didn't say were signs to the narcissist

The narcissist loves to read everything about you, not just the words you're saying.
You don't have to tell them something directly in order for them to pick up on it and store it as information. The gaps you leave are filled in with everything that you don't speak about, because the narcissist is so good at seeing where you stumble or stutter, and knowing that behind it lies a bad experience, or a bad memory that has affected you since.
Imagine you don't speak with your sister, and you mention her briefly before quickly changing the subject. The narcissist will sense your unease and know there's a back story there to be explored. For now, all they need to know is that you've got a history, and that it is complex.
If you apologize for something that isn't your fault, the narcissist will take a note of that, too. They know that people who over-apologize tend to come from a place of people-pleasing and wanting to keep the peace.
See alsoIf You're Dealing With A Narcissist This Survival Guide Changes Everything
If you ever had an uneasy feeling that the narcissist always knew which buttons of yours to press, I urge you to think about all those times you've been around them and unknowingly given them information about you that you've never told anyone else before.
Narcissists only pay close attention to you because they're constantly trying to strategize their next move.
It's not about love.
The painful part is how good they are at convincing you it is love.
4"I know you better than anyone"

Of course you do (rolls eyes).
This line for me is one of the worst lines I'm told narcissists use on their victims, and yes, it sounds like all your dreams have come true.
You really believe it when they say how much they know you, and how well they've listened to you and your stories.
You think it's brilliant, lovely, heartwarming that someone could want to get to know you that well, and you feel special.
What they really mean is this:
"I've spent all this time getting to know you and filing away everything there is to know about you. I'm confident that I can use any of them at the drop of a hat; now I am in control."
Being told that they know you better than anyone should really be seen as a warning; they own all information about you, and have been meticulously collecting said data from the moment they met you.
"You belong to me."
If they could say that and get away with it; they would.
See also4 Lies Every Woman Should Tell A Narcissistic Man To Protect Her Peace
5Notes between narcissists are shared and compared

If there is a narcissist already present in your family or social circle that you now share with this other narcissist, then expect them to find each other and start talking. They both have a set of notes about you that can be compared right off the bat, and they'll believe that everything is true.
These two people tend to work together to leak things about you, share personal details with other, unsuspecting people, and be very good at casually mentioning your name if it means they're able to then get some gossip or news about you from a person who doesn't even know the meaning of the word narcissist.
It's funny isn't it, how narcissists really don't like anyone but use up so much of their day talking about those very people.
Be prepared here for things about you to come up that you said or did seven years ago, or how much money you earned in your first job, like it's some kind of problem.
Narcissists are responsible for whatever leaks about you. Every trail can be sourced back to the original, toxic person.
6Knowing why gives you a little power

Knowing why a narcissist does this is going to really help you moving forward:
See also5 Creepy Things Every Narcissist Hides Somewhere in Their House
They just love control.
They're obsessed with having it and retaining it, and they want to see you helpless as a result.
If they know your triggers and fears, they can hold a very large amount of power over you, which is what they want as soon as they lay eyes on you.
Narcissists act like they care:
Don't be fooled.
