There has never been closure on "General Hospital" for the characters of Claudette and Nicholas. Both are presumed to be dead, at the hand of Nicholas' cousin, Valentin Cassadine. Ava saw Valintin shoot Nicholas, and watched as he fell over a balcony. No body was ever recovered. Claudette was last seen on an airplane, with Valentin seated beside her. Is it possible that both are alive and well on Cassadine Island?
Claudette's tale
Claudette came to town as Nathan's ex wife, with a daughter Charlotte in tow. She first said Nathan was the baby daddy, then later claimed that Father Griffin was the little girl's father.
Eventually it was proven that Valentin Cassadine was the biological dad, and Lulu Spencer's egg was used to produce the child via test tube. Claudette was only the surrogate. Shortly after revealing her connection to Valentin, Claudette disappeared. She boarded a plane, but was not seen exiting. It's assumed that Valentin had done away with her. No word has come forth regarding Bree Williamson and her role as Claudette. It's possible that she may be on Cassadine Island, and fans may see her again.
Prince Nicholas may be alive
Tyler Christopher, who portrayed Prince Nicholas, has been seen at "GH" events. He has hinted at a return to Port Charles, but nothing definite has come forth. As no body was ever found, it's more than probable that after Valentin shot the prince, he had him taken to Cassadine Island to recover.
The Cassadine estate is huge, and has many rooms and levels. There are also the catacombs and tunnels underneath the mansion. Over the decades there have been a number of individuals held captive there.
There are a lot of questions that have not been answered regarding Valentin. Viewers do know that he felt entitled to all things Cassadine, because he was left out of the loop, and not acknowledged as part of the family.
Helena Cassadine, the family matriarch, has brought back family from the dead, and even returned a few times herself from the great beyond. Because of this, it is reasonable for fans to believe that Nicholas and Claudette are somewhere around the his family's abode, and it's only a matter of time before the plot unfolds. Who knows? Helena herself may emerge yet again from the realm of the dead.