Robin becoming a side-character rather than the Prince in the Little Sea-Maid seems to be a plot-hole after it's revealed in Episode 33 by Captain Hook that Prince Charmings take the role of a prince in the story (if the prince isn't the main character in the story). When it's addressed in the premiere of season 2, it's revealed that [Robin might be more than she appears to be as the Fates point out that being able to change your role can be through a strong will or magic.
Tank's super strength was something strange, considering his size, Robin even Lampshaded this at one point. However, after it's revealed that Tank was a former Prince Charming that was allowed to keep his human form's strength, it explains a lot.
The Fates explain that each Prince Charming has a "True Tale", a story they can learn most from (aka have Character Development). Take a closer look at them:
Robin's True Tale is "Beauty and The Beast" with her as the role of Beauty, which tells the tale of a girl learning to love someone not for his looks, but for the person they are. Before becoming a Prince, Robin was a shallow girl looking to marry a rich hot guy.
Tank's True Tale is "Orpheus and Eurydice", a tale of Star-Crossed Lovers and dealing with grief. Tank had just lost his parents and found himself unable to move on from that grief.
Batsinda tells Robin Damian's True Tale is "The Wizard of Oz". A few chapters later, we learn Damian has parents in a failing marriage, and the message was for him to learn he has the power to change things all along, just like Dorothy had.
With the reveal of Damian's past, it's no wonder he latched onto Batsinda. He probably saw her as the mother he wanted to have.
Due to the Wicked Witch's meddling with the fairytales, all the fairytales have unhappy endings. Meaning characters like Snow White stay asleep forever, and Sleeping Beauty dies.
It was implied in episode 11 that Tank most likely watched Red Riding Hood get eaten by the wolf.
Robin and Tank have to leave Sleeping Beauty's story due to the briar thorns in the way, trying to pass 100 years in the story. Meaning Briar Rose has been left to sleep for 100 years.
The very fact that everyone from Forever After used to be people from the Real World and that most of the villains, especially the Witches, are viciously killing off the Prince Charmings, who are the only people who can free everyone, is chilling.
Lampshaded by Robin, pointing out that the Fates don't seem to care whether or not people had lives before, or whether or not they get traumatized through the experience.
When Robin finishes Snow White's fairy tale, Snow White becomes nervous and starts asking what will actually happen to her once the story is over. Robin ignores her and reads the happy ending anyway. We never get an answer to Snow White's question.
The question actually gets answered in episode 69 and it makes the situation even more horrifying. If a story is closed, the characters in it reset back to the beginning, losing all of their memories. As the Wicked Witch puts it, the people Robin got to know and helped are basically dead.
When Robin is cursed with blindness, Tank explains that they can't undo it until they finish the story and that if they go try to go to a different story, the curse will just follow her.
