Well, traditionally this combination is considered to be quite difficult! When two people are born under conflicting elements – here Water and Fire – it can be hard for them to fully understand where one another are coming from and their level of love compatibility is likely to be quite poor. In reality, though, things aren't quite as difficult as they might appear.

True, tensions can arise due to their contrasting ways of approaching things – normally quite confidently and directly when the Sun is in Sagittarius, but much more diffidently and evasively with a Piscean Sun.

Because Fire and Water have a natural tendency to extinguish each other, to be able to function harmoniously together, each has to avoid the tendency to cancel the other one out. The challenge for Sagittarius is, while firing its arrows far and wide, not to ride roughshod over Pisces' sensitivity – while watery Pisces, with all its insecurities, must try not to dampen fiery Sagittarius's natural optimism and enthusiasm.

On the other hand, Sagittarius and Pisces also have quite a lot in common. Respectively ruled, and co-ruled, by Jupiter – the planet of faith, hope and limitless possibilities – Sagittarius and Pisces are closely linked by their lofty ideals and common desire to make the world a better place.

Other signs may dismiss these two as impractical dreamers with a tendency to expect - and to promise - far more than is realistic or feasible. Okay, so Sagittarius-Pisces couples probably do go over the top with their big plans and grandiose fantasies - but they sure have a lot of fun together, chasing those beautiful rainbows!
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This was requested by @_thepack5eva