Aquarius is a fixed sign, but I’ve always viewed it as the nominal mutable, just like Virgo can seem like the nominal fixed sign. This is because the energy of Aquarius is inventiveness, but it is an inventiveness focussed on individuality, yet expressed in relation not so much to ‘society’ as defined by the institutional structures of Capricorn, but to the more fluid sense of a collective humanity. (Famous Aquarians include Virginia Woolf, Abraham Lincoln, and Yoko Ono.)