Is it permissible to take a promissory check from a person with whom an agreement has been made for a house building project, so that a fixed amount is paid to the lender upon the sale of the house, regardless of profit or loss?

If someone gives money to their brother, there is no harm in taking a document or collateral for it. However, the transaction mentioned is forbidden because its true nature is a loan with interest. If someone gives money to another for investment, and stipulates that the capital be guaranteed and repaid, whether there is profit or loss, then they are a lender. And if they stipulate an increase beyond what was given, then they are a usurious lender.