I guess I like a very rare combination, like me; introverts that really get passionate when they meet someone like-minded.
It's kind of a contradiction when you say "introvert", as most people think of people too afraid of their own shadow, but as one myself, I firmly believe introverts are not timid by default, they are only such in awkward or forced situations with people they don't want to be.
Introverts have crazy passion for things or people worth their time and attention. And there's nothing better than connecting with someone from the same life-vein as you and fully splurging out without restraint, haha.
Maybe it's why I like cats too. Cats and introverts might as well be the same thing; you have to work super hard for their affection and trust, but once you get it, it's unbreakable.
Those are the kind of people I hunt out, as friends and anything more than that.
But I generally can (and do) get along with most, so long as they can hold a conversation, but very few can actually keep up with me when I get going. That's where the rare breed come in.