Cliché Storm: A humble farm-boy discovers upon reaching manhood, that he is the last of his line, related to a villain by blood, is destined to take the throne, quickly becomes a total badass, inspires people to rebel against a corrupt king, even ends up winning the heart of a princess he rescues... fortunately that's just the first couple books. Book 2 begins with him being given all sorts of crash courses in history given that he never grew up educated and learning actual fighting techniques, and people getting in trouble when he goes out recklessly.
Prince Lucas the werelion is Drew's half-brother and everything Drew is not. An apprentice Necromancer, he began to lose his sanity after he murdered Lord Broghan in front of his cousin, and former fiancée, Lady Gretchen, under Opal's instructions. He goes downhill the moment he murders his father Leopold under the other Catlords' orders. His interest in Black Magic leads him to work with the Wylderman Darkheart to create the Wyld Wolves, who slaughter the Sturmlands' army, an act that disgusts the other Werelords. He then murders Duke Henrik to "save" Lord Onyx after he honorably accepted his defeat at his Combat by Champion. When he finds out that Gretchen's in the Dalelands he leads his Wyld Wolves in a bloody campaign to get her, killing several innocents in the process. He later kills Lord Milo in front of Trent, partially eating him. When his grandfather Leon punishes him for killing his father and tries to get him to regain some honor, he murders his grandfather as well. When he arrives to Icegarden to kill Hector for killing his mother, Vincent of Redmire retorts that he's only here to settle a petty grudge towards Hector for always being smarter than him.
Vincent the wereboar, the twin brother of Baron Hector, begins by inadvertently causing his father's death and then killing himself in an attempt to murder Hector. Capable of remorse and hesitation in life, Vincent's redeeming qualities vanish when he becomes a vile. Vincent slowly corrupts Hector into a murderer and torturer of innocents, selling out the Dalelands to the wicked Prince Lucas and seizing Icegarden through Hector. Vincent devours the spirit of Hector's old mentor, torturing Duchess Freya for weeks on end, and accidentally but remorselessly pushes Hector into murdering the totally innocent Queen Amelie. Finally sick of his brother's hesitance, Vincent overtakes and fully possesses Hector himself, rechristens himself Lord Blackhand, and begins systematically murdering and resurrecting all of his own allies as the undead. Vincent starts resurrecting the dead by the thousands to slaughter all in their wake, decorating Icegarden's walls with the bodies of those he's slaughtered and driving his legions in a crusade to destroy whatever cannot be dominated. The series's finest demonstration of From Nobody to Nightmare, Vincent of Redmire eventually dies as one of the greatest threats to have ever scourged the Seven Realms.
First 2 books & fourth book: Vala the wereserpent is the self-proclaimed goddess of the cannibalistic Wyldermen, who offer her human and werecreature alike. Defeated by Drew, she plotted her revenge against him and those he cares about. First she killed and impersonated the crone Baba Korga, pretending to be an ally of Whitley and using her to enter Five Oaks unnoticed. During her "friendly talk" with Whitley, she revealed her biggest atrocity: During the journey, she devoured innocent Romari children when no one was watching. She then explains her intentions of turning the Dyrewood into her realm, where she and the Wyldermen can kill and eat with impunity. She also mentioned her plan of using Whitley as bait to attract Drew, and in an act of "mercy", she promises to kill Whitley quickly after she had dispatched Drew. Prideful, petty, and convinced that she had the right to kill and devour whenever she wanted, she saw humans as nothing but food and other Therianthropes as weaklings.
Storm of Sharks: Deadeye the wereshark, the captain of the Hellhound in the employ of Lord Ghul, makes a name for himself on the White Sea as a practitioner of brutal violence and rampant cannibalism. Attacking the smuggler ship Lucky Shot upon learning of the presence of werelords on it, Deadeye slaughters many of the crew himself and eats its captain alive before taking those who remain as his prisoners and slaves. Holding a special affinity for the werelord Whitley, Deadeye subjects Whitley to his perverted attentions whilst keeping her collared, informing Whitley's intention to make her his bride in between subtle hints of violence. Upon being attacked by the Maelstrom, Deadeye snaps and starts massacring both enemy soldiers and his own men, brutally tearing apart Captain Ransome's young friend Hob shortly before his own death.
Cosmic Deadline: The ending can feel rather sudden, with just about all the greater threats being dispatched at the end, and only two chapters after the climax really gives a resolution, complete with Trent's infection being cured entirely offscreen.
Moral Event Horizon: Hector either crosses it when he tries to kill Vega, or when he changes his mind about sparing 9 year old Pick.
While Lucas is no stranger to this (and likely crossed it within book one), in-universe, he seems to cross it when he mauls Milo to death.
They Wasted a Perfectly Good Character: The other lions - Leopold's father, during his brief screentime, shows that he is as passionate as all the other Catlords, but has far more reason within him than his son and grandson. Despite him holding a strong Lion shall not bite Lion rule even he sees Lucas is a Complete Monster and is pondering breaking that rule just for him. Sadly, Lucas kills him, and we do not get to know of things from their point of view.
