You'll be serious and intense when you're together. You'll both really appreciate the effect you'll have on each other. Whereas other friendships in your lives might be more superficial, allowing time only for small talk, this one will be more intense and focused.
You'll discuss all the deeper, more complex and weighty issues that you both might wonder about -- the intricacies of your friendship; your pasts; death; psychology. This person will help you deepen the ways that you think and communicate, and you'll help them with accessing and translating their deepest thoughts and feelings. As time goes on, you'll probably find that you feel a greater sense of understanding for yourself and your place in the world thanks to this person's influence in your life.