I am a web developer working on a business idea and "hired" someone to do all the designs for me. The designer I hired has an LLC, we both made a verbal agreement that the design work will be done in exchange for 10% of my idea.
I have a working prototype and the design is the only thing that's left to be done. I'm planning on incorporating in the near future, but that's still months away and the plan is to incorporate as an LLC.
My question is, how can we get past the verbal agreement and move onto a more formal one so once the business is up and running, this person owns 10% of it? Can this be formalized in some way without having to set up an LLC? Would a letter or email be enough proof if needed in the future as evidence in case any of the parties fails to deliver?