The phrase "fierce advocate" refers to someone who strongly and passionately supports a person, cause, or idea and vigorously fights for it. Full definition
Just know that our attorneys are here for you, and are fierce advocates of your rights, but also, for your family's best interests. (jpalmerlaw.com)
A bureaucracy can not be as knowledgeable or as fierce an advocate as a parent who must face the consequences of their educational choices daily. (empowerms.org)
Quite often, parents become fierce advocates to make sure their children receive the services, therapy, schooling, and inclusion they need and deserve. (verywellfamily.com)