Mere days before he was pronounced Crown Prince (and soon to be crowned King of the Pocket Kingdom), James vanished while on a picnic with his family. According to rumors, he wandered away when Queen Melissa I, which is his mother, wasn't looking and got lost. A few days later, Melissa passed away from Abtonin.
His family spent all of their time and resources trying to find him, but after a year, he was presumed dead, and Ava was made Crown Princess of the Pocket Kingdom (and later becomes queen, along with her sister) instead.
A few years later, James returned home with no memory of who he was, though he recognized Ava and Eva (but as old friends, not his sisters).
He constantly flirts with Eve, but instead of falling head-over-paws, she likes him less and less and due to them being first cousins.
Eventually, James loses interest in Eve and starts dating Lili. They later married.
Prince James: "Pocketville: Rise of the Blood Moon" Version