Complete Monster: Duke Roger of Conté, Alanna's Arch-Enemy, was originally heir of his cousin King Roald before the birth of Prince Jon bumped him down the line of succession, and he stops at nothing to get his place back. He creates a Mystical Plague that kills many in the city of Corus before it reaches its intended target, the royal family, who were deliberately targeted last so that the palace Healers were too weak to save Jon's life. When this fails, Roger's second attempt on his cousin's life involves goading Jon into getting himself killed by exploring a cursed city. Alanna foils this too, so Roger sends multiple Animal Assassins after her, tries to drown her, turns her friend Alex against her so that he tries to kill her while sparring, and helps create a war with Tusaine so he can pull a Uriah Gambit on both of them. After the war is ended without his intended results, Roger casts a wasting sickness on his lawful aunt, the Queen Lianne, using a wax doll of the Queen, being periodically run under a stream of running water that slowly drains her life force; this wrecks her already-poor health enough that she dies little over a year after the spell has been ended. When Alanna uncovers this plot and finally exposes him, she kills him, but that doesn't end it. When Roger returns he has become a full-blown Omnicidal Maniac, who gives up regaining the throne in favor of destroying Tortall with an earthquake out of spite. Not even his own followers (except Alex) are told, most thinking that they're participating in a standard usurper plot and not realizing that he cares nothing for them either.
Values Dissonance: George shows romantic interest in Alanna when she's eleven and he's eighteen, and stalks her for years, and yet is presented as a perfectly fine romantic option. Readers today tend to view that as squicky at best and verydisturbing at worst. Tamora Pierce has gone on record stating changed values do make this a lot creepier now, and this is even the part of everything she's written that she most wishes she could go back and change.