I’m just going to lay out my headcanon concerning Eric:
Hook is Eric.
Eric was born a Prince in a kingdom far away. As a young boy both his father and mother died and his vengeful uncle, who most likely killed his parents, was out to kill Eric so that he could not take the throne. Eric was stolen away in the night by his mothers most loyal servant and raised not knowing his true heritage. But then the loyal servant died and Eric was forced to make his way in the world. He took up with Davy Jones and came to see him as a father figure, even though Davy was a terrible man who did not love Eric. Eric changed his name in order to win his new fathers approval to Killian Jones. Then Davy abandoned Killian but Killian managed to be picked up by pirates, the Captain of the ship grew to care for Killian and made him his heir. When the Captain died, Killian took over as Captain of the Jolly Roger and decided he wanted to travel around FTL. And then one night, he walked into a bar….