Profits Interests and Non-Service Providers

Can profits interests be granted to non-service providers?  If so, how do those work?  

Alternatively, can unit appreciation rights be granted to non-service providers?

A true partnership profits interest generally must be granted in connection with the performance of services to or for the benefit of the partnership, at least to fit within the IRS's safe harbor. You could grant a partnership interest that looks and acts like a profits interest to a non-service provider, but they wouldn't have the benefit of the safe harbor that most profits interests are structured to comply with. 

Generally, I see appreciation rights to non-service providers (i.e., lenders, investors, etc.) in the form of warrants.