waif

The original legal definition of a waif denotes a piece of property found and, if unclaimed, falling to the lord of the manor. The more contemporary definition is of a person who is fragile, helpless, and uncared for.

In the context of kink, a waif is someone who seeks a strong, nurturing figure in their relationships. They typically play the role of the ingénue (a person who is endearingly innocent), and uses their innocence/helplessness to elicit the protective instincts of their Top.