A professional is hired by a client who needs their expertise and services, either for a particular project or in perpetuity. The client depends on the skill and guidance of the professional, while the professional depends on the client's clear vision and expectations. Examples of this kind of relationship include a lawyer and client, doctor and patient, and a graphic designer and customer.

Below are a wide range of dynamics that may accompany this relationship. Use the ideas that suit your story and work best for your characters to bring about and/or resolve the necessary conflict. 

A purely professional relationship and a situation where both parties reach a satisfied outcome
A professional who listens to a client's needs and understands their objective
A client who is clear about what they want and engaged in the professional's process
A client who trusts and respects the skills and experience of the professional
A professional who is clear with the client about realistic outcomes
A professional who meets a client's needs but takes advantage of them financially
A client who makes demands that are beyond the professional's scope of work
A professional who fails to deliver the services a client needed or expected
A professional who overstates their ability to meet the needs of a client
A client who questions and challenges the expertise of the professional
A professional who fails to listen to the client and exercises their own opinion 

A professional requesting more money than was originally agreed upon
A client changing their objective after the work has already started
Either party being a poor communicator
Either party falling into financial hardship after the project has begun
A professional realizing that the scope of work is greater than they originally believed
The client receiving external advice that conflicts with the professional's guidance
A professional missing deadlines or failing to check in with the client