It's easy.

If you give me the feeling of being safe with you and I like you I will put my protective wall down and open up.

I will promise you to trust you even if everything around me tells me not to.

But if you give me the feeling that I'm not safe around you, what will probably lead to not liking you, I'm going to be most mysterious person that you probably ever met in your life.

I won't tell you what I'm thinking about all the time neither will I speak about my childhood or what inspires or drives me.

So give me a reason to trust you and you'll find in me the most loyal friend you ever had.