Empress

Nena carries Empress, a Stand chained to her own blood rather than a free-floating humanoid. It debuts as a tiny droplet, and its real form only emerges after that blood makes contact with a person. On the victim it begins as an itchy little wart resembling an insect bite, then swells and gradually develops a face and limbs. Before long it looks like a small woman protruding from the host's flesh, topped by a pair of crests and wrapped in a shawl. Colored editions show it as red, at times with golden trim. Its namesake, the Empress tarot card, stands for burgeoning new life, a fitting clue to how the Stand operates.

Empress operates through parasitism. Nena first has to plant it by pressing her blood onto a target through contact, after which she steers it remotely. The bloodied patch balloons into a fleshy bud that keeps growing so long as it is fed, consuming anything smaller than itself, be it insects, fruit, or whole chickens. In time it reaches a humanoid shape and turns actively hostile, laboring to obstruct, wound, or slay its host. Against Joseph it first framed him for murder, then, once it sprouted arms, battered him with cookware and sought to hammer a nail into the back of his neck.

Since it fuses the victim's flesh with a Stand, it inherits traits from each. To ordinary onlookers it registers as a mere wart, only a Stand can injure it, and a coat of tar can lock it in place. The fusion also affords a grisly bonus: should Empress devour a victim entirely, Nena can crawl inside the emptied body and speak with that person's former voice, betrayed by almost nothing beyond a small polyp on the tongue.

Nena is the lone user, and Empress appears to echo her personality, coming off as mocking and rude as it showers insults on Joseph, its hapless host. For all the danger it poses, the Stand is physically weak and unsophisticated, which lets Joseph outsmart it and finish it off with Hermit Purple.