Please elaborate for me, the partner relationship of Builder and Private Money Investor, that is so elusive. ?  

One deal in particular: I had the opportunity of working 50/50 on net profits, with a private money investor. I post the checks and receipts to a spreadsheet, as a transparent basis for "at cost" renovations in lieu of "skin in the game". I found the deal, I bring the investor, and I bring the labor; the investor bought and paid for the whole deal in 1st position via Self Directed IRA.

As a licensed contractor, I feel that investores need a strong and trusting relationship with a contractor (Value Proposition). Otherwise, they are trying to project manage materials and crews in a process that they're generally inept. My skin is at cost numbers vs. Profit; usually 30% and more for retail. 

My investor, later in the process, began to feel that the deal was inequitable.  Never the less, we successfully finished the job and ended up splitting close to $100K.

I won't get into the "passive agressive" nature of this person that soured our relationship, but the investor came back to recognize the absolute need for a contractor, by no admission, but for returning with a request for quote on their own attempt of a total gut rehab with one of their finds.  

So, Do I Profit on the rehab, "and" put skin in the game, or do we work transparently as partners should?