You have two problems, it seems. First, you need to figure out what you want to do. E.g. do you want to join them or stay with your current arrangement. Nobody

You have two problems, it seems. First, you need to figure out what you want to do. E.g. do you want to join them or stay with your current arrangement. Nobody on this forum can help you decide that. But make your due diligence on the company before you make up your mind (For one thing - figure out why that other guy left). Assuming you do prefer to join them, you need to figure out what your price is. You seem to be afraid to make unreasonable demands, as you are in a position of power here. I would suggest that you take the approach of calculating what you believe your value is in terms of money per time unit (monthly, hourly, whatever). The difference between that number and what they can pay you should then be considered investment into the company and you should get compensated for that somehow. Most likely through equity. Calculating your value is a much more objective task and therefore less fraught with tactics, feelings and whatnot. Just remember to calculate your value for the company in the current situation. In this case, your value is clearly very high, so it would only be fair to factor it in.