I’m in a dilemma – not sure if 
Few months ago an ex-colleague of mine returned to India from abroad and sent an email with the outline of an idea. He had earlier developed a healthcare-related app and exited / folded the venture and was looking for a new venture.
I quite liked the idea of working with him & also the idea he pitched as it is related to the field that I’ve been working on since past few years. Enthusiastically, I exchanged few emails about how this idea can be expanded to cover more needs that exist in the market.
Recently, we met to discuss things in detail. At the end of the meeting I realised he is not looking to incorporate a company and formalise the venture but he is interested only to develop the product and start selling it. When I asked if we would sign an agreement to spell out the work arrangement he mumbled something that sounded like ‘no’.
I think he works on many ideas with different people at the same time and would exit them within few years with no long term commitment in any of them.
Since I am passionate about the idea, I continue to provide inputs, insights, details, data, etc. to develop a product based on this idea. However, I have a nagging feeling that I may be cheated out of my time and profit if I continue to work on this with no formal setup and written agreement.
How do I avoid becoming a sitting duck and cover my bases without sounding pushy & distrustful? Would greatly appreciate your ideas & inputs!