To anyone who knows them, they are complete opposites. He is constantly engulfed in risk and excitement, and loves every moment of it. All she wants is peace and stability, two things that could be unbelievably hard to obtain if their worlds mixed. Ask anyone, there is no way a relationship like that could work. It is an utter impossibly.
Yet, his bright, searching eyes find exactly what they want in her, and all she ever needs is to look into them and her life falls into order; everything is okay. And to her, the world would come crashing down without him as an axle for it to spin on.
They know each other so well that they are able to have entire conversations without saying one word. Yet, he could never become board of her, for he continues to realize more and more who she is. Every word she speaks, every action she makes, and every emotion she expresses opens up yet another angle to see her from; another side of her that he can explore. As for her, he never ceases to surprise her with every new secret he unfolds; every thought he has.
Yes, every risk he takes causes her to worry, and every effort she makes to calm his independent spirit may cause him some irritation; they always end up balanced. Without her, his world would likely spiral out of control, while hers would become so routine and empty that her life would not be a life at all, just an existence.
No, through every bickering match and fit of laughter they share, they become less of "you" and "I", creating a single "us". That is all they have been searching for and need: the "us" that they make up, that will split apart and recreate the "you" and "I" that they no longer recognize.
Every "you" has an "I" that can be found, and they have a greater effect on each other than anything else ever will. That "us" that the risk taker and the control freak have created, that's what lasts the longest, that's what is of the highest importance.
Though their togetherness was, and still should be an impossibility, never able to happen, they do not care about possibilities and impossibilities. Their only care is the "us" they have become.