The details of Prince William and Kate Middleton's sometimes-on, sometimes-off relationship are easily skewed by tabloid reports and unidentified sources. Some say they've been rocky at times because the prince wanted to party and have fun, while Kate wanted to get married. Others say that Kate was using her beau's royal status to make a name for herself.

We may never know all of the details of this duo -- with the exception of Diana, the royal family has never been known for their loose lips. What we can do, though, is take a peek at Prince William and Kate Middleton's astrological compatibility and see what clues we dig up.

Sun Sign Compatibility
William is a Cancer, and Kate is a Capricorn, two overly cautious signs that might have a hard time getting a real relationship off the ground. With these signs, if William really feels Kate is the right one for him, he'll do everything in his power to break down her defenses, and will be successful if she feels he's the right one for her. And not that a member of the British royal family would ever discuss it, but these two signs should have great sexual chemistry.

Mercury Sign Compatibility
Both William and Kate have their communication planet in Air signs, making them great conversation partners. William's Mercury in Gemini suggests he loses interest quickly, but Kate's Mercury in Aquarius is intellectually quirky enough to keep him stimulated. However, William may be prone to making promises just to make his partner happy, and then never following through. Like, making someone a princess, perhaps?

Venus and Mars Compatibility
The placement of William and Kate's Venus and Mars signals good news. Both share a love of beauty and the finer things in life, although Kate's unconventional streak may upset William's more conservative nature. They're likely to have a life of great adventure, great sex and of course, all the great advantages that come with being royalty.