I still think Hook concocted that father story to draw out and manipulate Bae. Just as he lied to Belle when he met her, and lied to Aurora too when he “freed” her but really had stolen her heart. He lied to Rumple about Milah when he came to rescue his wife. He lied to Regina to trick her into wearing the cuffs. He can seem really genuine when doing these lies, but that’s why is a good pirate. I’m not sure about his combat skills (Beaten with books, cane, umbrella stand, and a compass), but he is really good at deception and trickery. We’ve seen his sleight of hand over the bean against Rumple, then later Emma. There’s a back-story here I think about how he came to be this way, rather than the brute-force kind of ruffian Pirate.
Also, I don’t see a mid-30’s actor playing against Colin as a father either. A brother or friend, on the other hand, works perfectly. IT could also parallel some betrayal in present day storyline too, if that skeleton key clue was a nod to the storyline in the episode we saw the key.
So I think maybe Hook got the JR by tricking someone, and that might have led to Charming’s ancestors losing their kingdom. Not to Charming’s father himself, but that lineage. Yet it is convoluted really to try to show that, except with a clue like the crests.
If Liam is in Hook’s backstory, it may also be pre-curse but post-NL backstory too–we do not have the story of HIS escape from NL, and how he ended up in Regina’s castle.
Did they say we’ll get to know how he became a pirate, or just backstory in general?
“If I had a world of my own, everything would be nonsense. Nothing would be what it is, because everything would be what it isn't. And contrary wise, what is, it wouldn't be. And what it wouldn't be, it would. You see?” -- Lewis Carroll, Alice's Adventures in Wonderland & Through the Looking-Glass