Aquarius is a moody and ill-tempered Celestial Spirit who often threatens to kill her owner, Lucy. While other Celestial Spirits serve Lucy obediently, Aquarius is irritated by her. When summoned, Aquarius will either attack the opponent, Lucy, or both of them, depending on her mood.Despite this, Aquarius does care for Lucy's well-being. She is very kind and loving towards her boyfriend, Scorpio, to whom she shows a completely different side of herself.