More seriously (even if the emoticon is a real one), I think we both had been looking for the opportunity to meet a co-founder for a long time. Maybe he disagrees, but I think we both had a clear idea of what we wanted and what we wanted NOT.
I registered our current startup URL, 1y1/2ago, I personally had presented a project idea to several handful of hackers before we met each other. It is like when buying a house, you see many, you sharpen your judgment & taste, but when you find the one: you sign very quickly, because you have that deep warm gut-feeling.
It does not mean everything will be rosy all the time. I think we both already know this.
But the one key element for me was a true sense of respect. This guy had sharp comments from day 1. Different ideas of how to go about the implementation (I already had put a prototype together with the help of another engineer (more than hacker)) we threw this away and restarted from scratch, thanks to his input.
He was understanding the idea from day 1 because he is that type of driven person, in sports, hacking, and a demanding human (his NYTimes covered app may shock some). He is international minded, open. He share the same crazy goal on our startup 1st $M.
I learn with him a lot, I discover a lot, it is all exhilarating, and the guy while being good at what he does and in general (to use a litote;), he still has this down to Earth humbleness. Respect.
And this respect emulates me to do my utter best so that our startup kicks a.. and so that on my part I don't screw up that chance. From what I see in what he does, it seems he feels the same. Grateful.
There are few times in your life when you think you are in front of a positive black swan. Maybe we see our startup as something bigger than ourselves, maybe we share that sense of awe.