Was that what she wanted? She had no way of knowing whether the boat would recognize her as an adult or not, and she needed someone to go along with her who wouldn’t be recognized by the magic, like a house elf or a child. However, she did need someone who could draw the boat up in the first place, and furthermore defend against Inferi and have the strength of will to force a potion down her throat. Sure, Vici could Apparate her to the cave, but could she fight off hordes of the undead? Could she really do something to harm Hermione, whom she loved with single-minded devotion? What about if Hermione begged her to stop, what then? No, she really should take along a wizard, and Regulus was volunteering for the position.