Expansion is something both of these signs specialize in. Sun in Sagittarius broadens his external horizons, while Moon in Pisces consistently shifts her inner boundaries. At times, Sag may be too overbearing for sensitive Pisces. But if he can tone it down while she builds up some of her defenses, they’ll be able to create a fantastically dynamic relationship.
Sun in Sagittarius pushes the limits. He doesn’t believe in restrictions, seeing them as inconveniences to be vaulted over (regardless of the consequences). While his gung-ho approach makes him a fun partner, his lover should be aware that he applies this attitude to everything. “More” is his philosophy, and restless boredom can result if he feels pinned down. He can also be a crusader for certain ideals, especially if they involve tolerance and justice. Sun in Sagittarius’ approach can be inspiring or annoying, depending on how important practical details and routine are to his partner (he tends to overlook the fine print).
Moon in Pisces dissolves the limits. Incredibly sensitive, she absorbs the energy of her environment, while maintaining a core of innocent acceptance. This makes having a positive, healthy partner and serene home life essential for her. Home should be sheltered, and allow her plenty of time to recharge. Moon in Pisces also needs a bit of magic in her relationship, and a lover who can provide this will keep her fulfilled.
Moon in Pisces will enjoy the adventure that Sagittarius’ brings to the relationship, but may find herself bruised from his blissfully unaware approach. Sun in Sagittarius won’t immediately appreciate Pisces’ sensitivities, especially if her Sun sign is more outgoing. Pisces will need to cement some of her boundaries, and Sagittarius will have to work on his empathy. If they can do this, these two will enjoy an unusually creative relationship with a strong, idealistic streak.
Would it lessen the tension of the square if Sag had natal Sun conjunct Neptune, since Neptune rules Pisces?