How are the Cassadine's royalty?

I've heard Helena and Stefan refer to Nikolas as Prince. Prince of what,exactly? I don't get it.

They're not actual royalty, just closely related (mostly through title rather than blood, I would imagine). Prince in Russia meant something different than Prince in the west; what we would call the king in Russia was the Tsar, and his children were the Tsarevitch (the heir), the Grand Dutchesses (what we would call Princesses) and the Grand Dukes (all the sons except the first-born; what we would call Princes). Prince was a noble title, not a royal one -- it was the highest degree of aristocracy underneath the actual royals, or could signify that the Cassadines belonged to one of the ancient dynasties that came under tsarist rule when Russia was united.

I like to think that it's the latter, and the Cassadines are one of those old formerly-royal families clinging to a dynasty that no longer exists, but it's never been specified on screen.

Nikolas is a Russian Prince and the current head of his family's legacy, Cassadine Industries. He is the son of Stavros Cassadine and Laura Spencer.

He was named Nikolas, after Tsar Nicholas II. His great-grandfather Mikhail was of noble blood and had been a close friend of the Tsar. It was only after Nikolas was born that Laura realized just what lay ahead for her son. The Cassadine family were Russian aristocrats, with connections to the royal Romanov family. They existed for hundreds of years in Russia until the Bolshevik Revolution forced them to flee to Greece. After that period they built a large economic empire of power and wealth. As the Prince Cassadine, when Nikolas came of age he would take his place as the head of the family and would have the power that came with it.

Mikkos Cassadine was a Greco-Russian aristocrat. The Cassadine family are descendants of the Russian aristocracy, with connections to the royal Romanov family. They existed for hundreds of years in Russia until the Bolshevik Revolution forced them to flee to Greece. After that period they built a large economic empire of power and wealth. Mikkos and wife, Helena Cassadine, had two children, Stefan and Stavros. He also had an affair with Kristen Bergman (real name Kristin Nilsson), an opera singer, and had two daughters, Natasha (Alexis Davis) and Kristina. Kristen Bergman was murdered in front of her daughter Alexis by Helena Cassadine. In 1981, Mikkos made his only on screen appearances on General Hospital when he was the mastermind behind a plot to attain world domination by holding the world to ransom through the use of a weather machine that could create severe snowstorms. He was eventually killed by Luke Spencer when Luke foiled his plans. Nevertheless the spectre of Mikkos still features prominently in storylines of General Hospital as his widow Helena, daughter Alexis, grandchildren Samantha McCall, Nikolas Cassadine, Kristina Davis and Molly Lansing and great-grandchild Spencer Cassadine are still a part of the show.

http://en.wikipedia.org/wiki/Mikkos_Cass...

http://en.wikipedia.org/wiki/Helena_Cass...

http://en.wikipedia.org/wiki/Stavros_Cas...

http://en.wikipedia.org/wiki/Nikolas_Cas...

They are Russian/Greek royalty.

Nikolas is a Russian Prince. He is the son of Stavros Cassadine and Laura Spencer. And the current head of his family's legacy, Cassadine Industries.