Thoric's father is unknown; Michelle isn't telling. Thoric spent his youth being dragged all over creation by his mother on diplomatic missions, and has thus acquired an extensive circle of friends all over the Golden Circle. He's a generous man, said to have been a coward in his youth, though it's hard to believe that could have ever been true these days, as he is generally well-regarded by the family as brave, generous, and gentle. He's also a potent warrior and humongously strong, carrying the Arcadian Patternblade Frostrazor. (Certain confused stories claim he possessed it during the Herald Crisis, which would be theoretically impossible, given the Arcadian Patternblades postdate the crisis.) He is also a sorceror of some skill. And King of Arcadia in his spare time.
Thoric's heroic deeds during the Herald Crisis are too numerous to describe in detail, though he first made a major splash with his leadership of an Ewok army on Endor and with his successful grappling of Kenshin (who was subsequently killed by Jacqui) during the battle of the Serpent's Horn.
Thoric is on good terms with most of the family these days, though he and Kozue get along poorly, as he takes great offense at the bile she spews at his wife. They mostly avoid each other since a Rose Duel nearly a century ago in which Kozue lost and lost badly, much to her shock. Thoric seems to get along especially well with Prince Beowulf, Princess Kanna, Prince Ramon, Princess Keiko, and Motoko's Quartet. (And of course, his wives, Jacqueline and Mutsumi. Theare are continuing rumors of a yearly Triumvirate and Quartet tryst. His easy intimacy with Motoko at public occassions has tended to further these rumors.). He has mixed relations with his father-in-law, King Miki, who likes Thoric, but doesn't approve of triple and quadruple marriages. He seems fond of his sister-in-law, Kaname, but gets along very poorly with Shinobu Major these days.
Thoric seems to like most of the younger generation, though not all of them return the favor. He is baffled by his son Ota, who is nothing like him, but gets along well with Princess Makoto, his daughter by Mutsumi. Thoric has been known to lecture Miroku on sexual responsibility, which usually results in Miroku pointing to Thoric's marriage and leaving Thoric lost for words. He finds Nanbara amusing, and seems to have a certain fondness for Kanako and Deirdre. He and Violet are known to enjoy each other's company, and he's been known to consult with Yomiko and Telemain when obscure matters came up. He and Aburatsubo get along very well. (Thoric seems to regard Aburatsubo as being very similar to his younger self, though Thoric doesn't have the reputation of having been more flamingly gay than the inhabitants of Big Gay Amber in his youth.) Thoric does not get along well with Captain Uotani, who apparently somehow mistook him for an intruder during one of his visits to Amber, and attempted to beat him up. (He didn't appreciate being thrown down the stairs, and she failed to appreciate him using her as a club to beat up her guards unit or the chewing out she got from Misato afterwards.) Captain Hanajima seems to regard him with suspicion for no apparent reason, and he's known to find her somewhat creepy.
Thoric spent a period of time as a woman, after being impregnated by Nemesis. He has since given birth and returned to manliness.
Thoric and his wives assisted in the defeat of Wu-Sakura's recent assault on Castle Amber.