You can rely on their willingness to help.
An example of to rely is depending on a bus to show up on time.
Relies on her parents for tuition.
Relied on them to tell him the truth.
Origin of rely
- Middle English relien to rally from Old French relier from Latin religāre to bind fast re- re- ligāre to bind leig- in Indo-European roots
From American Heritage Dictionary of the English Language, 5th Edition