[bacheson1293]

It's important to determine whether or not the person is qualified and capable. While questions have their merit I'd recommend a more creative exercise.

If you have the means, take a trip half-way across the world and live in close quarters for 3 weeks together (while you work to get the business off the ground). If you can't stand them by the end of the trip; walk away.

I've been working with my cofounder for 15 years now and together we've accrued more than ~$30M in combined revenue from a handful of projects. Being able to argue, disagree, make a decision, move on and then grab a beer after work like nothing happened is paramount. Your personal relationship with this person will be the first domino in every decision you make.

[tacon]

Clint Eastwood was on some talk show long ago, and he was asked about relationships, girlfriends, etc. He said he tests potential girlfriends by going on a three-hour driving trip. If they still have anything to talk about at the end of three hours, they have potential. I think that would apply very well to cofounders, too.

[tacon]

And a simple test of how well two founders work together is to take a two-person canoe down a course that demands teamwork. Be sure to switch off who is front and back. I've seen couples descend into cat fights in a canoe.

[maruhan2]

How about a botlane duo in league of legends

[ovatsug25]

Great idea!

[showtimes]

This 1000%. I've been with my co-founder for about 10 years, 3 companies and one acquisition. We're actually related but that didn't matter cause we didn't know each other THAT well. Being able to argue and have a beer after is the key here because it shows its not personal and that the other person or you care enough about your idea to defend it.