A popular variant typically worn by females is a tattoo resembling a heart-shape, which (if magical) usually has the effect of increasing the wearer's libido and/or fertility. In many cases it is also evocative of (and positioned over) the uterus. Sometimes used as a "mark" that person belongs to someone.
A famed example is Olga Discordia, whose primary sex scene revolved around the gradual breakdown of a womb-protection spell, as indicated by such a tattoo.
