Before the Spring War, Regal was happily married to Esther and ruled Shubeth Village with her. However, her frail health caused him to seek for a method to restore her. This solution seemingly came in the form of the Dragon Nest given to him by Jude. Using magic, Jude made the Dragon's Nest seem like it was healing Esther, though the Nest would actually siphon away her vitality once his magic wore off. He also bound the Nest to Regal's life, forcing the Ancient Dragons to obey Regal's will.
With everything seemingly going perfect for him, Regal agreed to participate in the Spring War. He staged the attack on Shubeth Village to lure Temar away from Vavelia and provide Jude and the Pope the opportunity to slay Vavelia's deities. Using his control over the Ancient Dragons, he also created a reputation for himself as a dragon-slayer, though the rest of his squadron was conveniently killed during the battle. Only one survivor from the incident lived to know the truth, and he quickly disappeared afterwards.
Some time around the beginning of Witch Spring 3, several years after the Spring War, Esther falls comatose after Jude's magic on the Nest wears off and the Nest starts absorbing her vitality. Regal's apparent apathy towards her condition and tyrannical strong-arming of the other two villages in Derkarr antagonizes him to his son, Adrian, and causes King Raphael to send Johannes to curb Regal's actions.
Eirudy on the RunEdit
In the Light/True paths, the climactic battle against Regal occurs in Chapter 4. After digging up his shady activities and revealing the truth about the Ancient Dragon attacks, Adrian and Eirudy fight against him, Monnet, and an Ancient Dragon. After being defeated, he calls two more dragon reinforcements, only for them to be defeated by Pieberry and Eileen.
Pieberry and Luna, who came from Vavelia to announce the end of the Vavelian witch hunts, reveal the truth behind everything that's happened. Noting that Jude's magic on the Dragon's Nest was indeed gone, Monnet then lands a fatal blow on Regal as revenge for defiling the name of the Ancient Dragons and forcing her brethren to act as his sacrifices.
After she leaves, the truth about the Dragon's Nest and Jude's lies is revealed to him. He dies regretting his actions, but is grateful he managed to clear it up with Adrian.
Eirudy confronts him at the Village of Lehert's mercenary camp after finding that he was not at Shubeth Castle.
He pleads with Eirudy to save Adrian, who had taken his blow for her, but Eirudy is unable to use her Soul Stone to revive him. Instead, it even absorbs his remaining Vitality, and she flees after some of the Lehert villagers arrive.
Eirudy becomes a human-hunter after that event, but whether Regal was among her victims is unknown. If he lasted until Pieberry and Luna's arrival, or once Monnet couldn't sense Jude's magic on the Dragon's Nest, it is likely that she would kill him like she did in the Light/True paths.