Sympathizer

The employee was a sympathizer of the suggestion to implement a flexible work-from-home policy.

The student was a sympathizer of the idea of having longer recess time.

The friend was a sympathizer of the opinion that pets should be allowed in all public places.

The child was a sympathizer of the belief in the Tooth Fairy.

The historian was a sympathizer of the interpretation of history through cultural lenses.

The environmentalist was a sympathizer of the cause to protect endangered species.