I have an interesting au origin story for Tirek after his comic issue in “Fiendship is Magic”. As we all know, he didn’t always look like a demonic beast who feeds on magic: he was as human-esque as any centaur of his kind would be. But one day, a heated argument between him and his father spiraled out of control and he used his power on his father. Fearful of what would happen to him because of this, Tirek fled the kingdom and went into the badlands. Concerned for his son, Vorak took his guard and decided to pursue his son. They eventually converged on a strange cavern filled with pits of glowing, green substance. These were vats of dark magic from a time when the original ruler of this land, Tirac, reigned supreme and experimented with Dark Magic. Despite finding Tirek inside, Vorak also found a gang of rogue Gargoyles in there who attacked the king and his forces. A fight broke loose, and scared Tirek further into this “factory” of mystic proportions. Vorak managed to get passed the Gargoyles, and cornered his son above a stone catwalk. Still afraid, Tirek begged for his life, even though Vorak had no intention of harming him. But what neither counted on was the stone walkway being unstable.
And neither could predict Tirek loosing his footing, and falling into one of those deadly vats.
Tirek was drowning. The dark magic was burning his skin. Stretching his body, and twisting it around. He had no concept of time for how long he was in that pit. But eventually, fate had other plans for him, and he was sucked down a narrow hole leading outside. A chute that was spewing out the dark substance into the wasteland, and which spat Tirek out. His armor felt tight across his chest, and he ripped it off with ease. He didn’t know what had happened, but he was grateful to be alive, though he felt itching all over. And then he saw his reflection in a nearby puddle as the rain poured down. He couldn’t believe what he was seeing: he was covered in black fur, his physique had grown, his horns had also grown and there was something……sinister about his face. Like he had ascended from the Inferno itself. At first, all he could do was weep for what had happened to him. But then that changed: he was now laughing. As he rose up to his feet, he let out a maniacal laugh as he finally snapped. Whatever sanity he had left was gone, and replaced with something else - something evil.
And all it took was one bad day.
Vorak returned to his kingdom, feeling guilty over his son’s so-called death. He was unsure of how he was going to tell the rest of his family the news. He forbade the rest of his guard from telling anyone as he wanted to deliver the news, himself. But he would never get the chance as a mysterious figure entered his throne room. It was quickly revealed to be Tirek, alive and well. However, things were not well as Vorak soon began to notice as Tirek approached him. He was so relieved to see his son alive, he didn’t notice the differences in his appearance as his silhouette drew closer. Tirek blamed him for his present circumstance, and stated that he no longer cared for the throne: he had his sights set on higher goals - but not before he would have his revenge on the one responsible for his many years of reprimands, disrespect and humiliation. When Vorak pleaded with his son, Tirek stated that the king’s son is dead. As he stepped into the light, he declared himself “Lord Tirek”, and made the claim that he was much happier now. He then bombarded Vorak with magical blasts that penetrated his armor, and weakened him. But he didn’t kill him, as he believed leaving him weak and helpless was a fate far worse than death.
So he drained Vorak of his magic, and then imprisoned him alongside his former master, Sendak. When his mother learns of this, and tries to appeal to Tirek, he denounces her for never standing up for him. He then forces her into silence with a magic spell, and leaves her to grieve for the fate of her husband and son. And while Sendak tries to bargain his way to freedom, Tirek assures him that he no longer has need of him, as fate has provided him all the skills he needed to become an indomitable force. After abandoning his parents, and former master, he recruited his loyal brother to his cause to steal Equestrian magic as that land was a bounty of power that he believed belonged to him. He didn’t tell Scorpan what he did to their parents, and simply said his new appearance was a stroke of fate. Yet it was still him beneath his beastly appearance. Though part of him doubted Tirek’s word, he still believed in him and decided to join Tirek in his crusade.