You two talk up a storm from the first time you met. You give each other a lot of space for your individual opinions; you aren't scared by intellectual differences. In fact, you're invigorated by them!
And you're attracted to each other for your minds, for your easy mental connection that feels as if you've known each other forever. Even disagreements are interesting and fun, because you both recognize that you're getting to know each other and talking out your lives. And that feeling of familiarity, of a deep, natural connection? It could be that you knew each other in a past life, and you supported each other intellectually then, encouraging all of your best ideas to come to the fore -- even if they were unpopular or seemed outrageous. That same energy has come back in this life. Especially if there are other aspects between you that speak to communication and self-expression, this relationship is all about your intellectual bond and that feeling of natural closeness that is apparent from the start. Even if you don't end up staying romantically involved, this bond between you is such a great foundation for a relationship that you might be able to be friends.