Square · 90° apart
Square
Same modality, clashing elements. Genuine friction, and genuine momentum: this pairing produces change, not comfort.
Fire · Mutable · ruled by Jupiter
Brings. Genuinely open-minded and hard to discourage. Says the thing nobody else will.
Struggles with. Says it without checking whether it needed saying, and leaves before the consequences land.
In love. Needs room and honesty. Reads possessiveness as a threat rather than devotion.
Water · Mutable · ruled by Neptune (traditionally Jupiter)
Brings. Feels what other people feel, often before they do. Creative without forcing it.
Struggles with. Absorbs moods indiscriminately and retreats into fantasy when reality gets loud.
In love. Devoted and idealising. Prone to loving a version of someone rather than the person.
Sagittarius is mutable fire; Pisces is mutable water. Sharing a modality means handling change the same way, which sounds helpful and often means competing for the same role.
Sun signs are one factor among many, and astrology itself treats them as a starting point rather than a verdict. Two full charts describe far more than two birthdays do.
Computed, not asserted
Zodiac signs are not equally common — the Sun spends different amounts of time in each, so some pairings occur far more often than others. This one is 1.266% of all possible pairings, which ranks 61 of 78.
12 of the 78 pairings form the same square. Worth knowing before treating this aspect as a distinguishing feature of your relationship — a sixth of all couples share it. Note also the rising times: at London’s latitude these two signs spend very different amounts of time on the ascendant, which is why one of them turns up as a rising sign far more often than the other. The full table is here.