What does 'fair' mean? Life isn't fair. To make this easier don't think of this in terms of 'fair' think in terms if what you want. Start with the obvious; are

What does 'fair' mean? Life isn't fair. To make this easier don't think of this in terms of 'fair' think in terms if what you want. Start with the obvious; are you happy with the salary sans equity? Because, let's be honest, chances are the equity is worth 0. Assuming this fails (most startups do) will you be happy just walking away? What about long-term? If you're both there 10 years from now I'm guessing it's because you both made it work together? Will you be equal then? Personally I wouldn't ask for 25% in 6 months. I'd ask for 5% a year. For 10 years. (With any dilution taken into account.) And a decent salary along the way. (Same as him). Yes he's done work, yes he's put in money, yes he's proved thd concept - all valuable and worthy of reward. But after 9 years this head start won't matter as much.