Is my work as an assistant to my relative in importing goods, which I volunteered for and continued for years without a specific financial compensation, and then I started receiving amounts not agreed upon from the shipping company for my continued work, considered brokerage, agency, or trade?

If someone works for another without an agreement, the default is that they are a volunteer, unless they are established in a profession for hire, such as real estate agents, brokers, and those known to take a fee; these are entitled to a fair wage (ajr al-mithl). However, if one is not established in such a profession, they are not entitled to a wage except by contract, condition, or implied understanding. A volunteering agent is not permitted to take anything from a shipping company or factories, etc., without the knowledge of their principal, because what is paid to the agent is considered a reduction in shipping costs that belongs to the principal. Therefore, what was taken must be returned to the principal or forgiveness sought from them. It is possible to agree with the relative on a wage or a percentage of the profit later.