A Cradle To Grave Character. Through the Rule of Symbolism they are all the various stages of a man's life, death and afterlife. Prince Lír is the man in his youth. Bold, adventurous, virtuous though somewhat naive. He believes anything good is possible, even love between a mortal and immortal. King Haggard is the man in his twilight years when his strength and valor have long left him, leaving him miserable, pessimistic and cynical about the world. He has gained knowledge but lost his heart. He believes love is a temporary thing that cannot last. The Skull is the man after death, who has lost his life. Now longing and clinging for nostalgia and anything that reminds him of happier times among the living. The Red Bull is his soul, now given into his possessive lust to hunt and capture all the beauty that is unicorns, and keep it all for himself. Even as The Skull, there was still something 'good' to be found in his mortal remains. But as this raging spirit, he's lost his humanity, now more rampaging demon than man.
- One could argue, this was the curse, the witch placed on the castle when Haggard refused to pay her. The man and his domain are in an eternal state of temporal flux, doomed to coexist in their respective times together, until freed by a Unicorn.
- And this is about a unicorn who learns about love and friendship. Perhaps the Unicorn's story becomes the inspiration for future Equestrian society.
- The alicorns are descended from the unicorn who defeated the Red Bull. After all, everyone knows that Red Bull gives you wings.
- Alternately, something eventually caused the Unicorns to develop into the ponies of the show. However, the Unicorn who gained emotions eventually became Celestia because of how unique she was among the others. Whatever caused the change was something that was meant to make them more "human" as far as mind and emotions go, and wound up changing them to three variants of Earth Pony, Pegasus, and Unicorn (and different colors too). As the Unicorn was already different she was instead made into an Alicorn and became the embodiment of the Sun.
- At some point, there could be a reference to this if Angel Bunny writes a story and/or Twilight asks why Celestia never dates. She'll look rather sad and mutter something about a Prince Lir.
Schmendrick: She will remember your heart when men are fairytales and books written by rabbits.- Also, Shmendrick could be made to have been Starswirl the Bearded due to his immortality and extreme (if hard to control and direct) magical talent.
That is why he is only happy at the sight of them, but he doesn't know why - he forgot about the time long ago.
King Haggard used to be a unicorn himself but has been human so long that he has completely forgotten (much like Amalthea starts to do). The scar on Amalthea (shaped liked the sun) where her horn used to be probably faded with time on him. Also, when King Haggard looks into Amalthea's eyes, he doesn't see his reflection but rather the forest, after her being human for a while he can no longer see the forest in her eyes...this probably also happened to him. The unicorns being the only thing that brings him joy makes sense if he used to be on but cannot remember...like his subconscious wishes to return to his true form. His obsession with Amalthea is really him trying to find himself.
- To add to this, his design is somewhat reminiscent of a unicorn; His beard does look like the type unicorns are normally depicted with in medieval art, he has white hair and greyish skin (though the hair could just be a result of aging), his figure is very lean much like Lady Amalthea, and his eyes appear to be a similar pale purple. Additionally, the myths and rumors about him imply that he was not born the ruler of Hagsgate, having arrived as a conqueror, with no one knowing where he originally came from or his lineage.
I know; Schmendrick said that unicorn didn't have any children. But, if he were mistaken about that, then Haggard being descended from a unicorn and a princess links in to his royalty, his dissatisfaction with life, and his love of unicorns.
Haggard seems more of a warrior than a magician, so perhaps the wizard Mabruk taught him to summon the Red Bull, or summoned it himself and bound it magically to Haggard. Mabruk was the cause of all the problems in the story, and gets away with it at the end, because after all, "Nothing ever ends," and there's always another quest to complete or villain to defeat.
- It's what this troper always assumed. Mabruk's presence in the story is completely unnecessary and could have been removed with little to no changes. I think it very likely Beagle invented him purely to make Haggard controlling the Red Bull seem less strange.
- This troper always thought that maybe the Red Bull was a physical manifestation of Haggard's despair. When Schmendrick tells the Unicorn about rumors regarding the Red Bull, one is that the Bull keeps Haggard prisoner in his own castle. What if this is true, but isn't so much literal as figurative: the Red Bull is essentially Haggard's intense depression, made into a terrible creature whose only instinct is to seek out the one thing that makes Haggard happy? People who suffer from depression often feel trapped by it — and for many, it feels worst at night, which is when the Bull comes out from the bowels of Haggard's castle to seek more unicorns. Perhaps Mabruk, being a magician, took Haggard's despair and unhappiness and made a monster out of it.
- Combine that with the theory that Haggard was the unicorn turned human and its possible that the red bull is a manifestation of Haggards lost unicorn powers. It could have been any other creature, mythical or not but its a bull, an animal (non magic) with horns (his forgotten self). And he bears no I'll will towards the unicorns. He only wants to see them and keep them for himself. Hence the bull cannot harm them but drive them to him. And his agenda fits the logline of this film very well. A unicorn leaves her forest to find other unicorns. Haggard stayed where he was and instead had all the unicorns come to him.
- Unicorn says the Bull is way older than her, herself immortal.
It would explain the white hair, purple eyes and connection to a mythological creature. They also for some time think they are the last of their families/kin.
It's hinted at a lot in the story, but not outright stated.