The series consists of:
- Mouseheart (2014)
- Hopper's Destiny (2015)
- Return of the Forgotten (2015)
This series provides examples of:
- Battle Cry: Firren's "Aye, aye, aye!" She later reveals this is in tribute to Ira, who had a stuttering problem.
- Big Friendly Dog: Capone the bulldog.
- Big Sister Bully:
- Pinkie acts like this to Hopper and Pup at first, though she eventually mellows out.
- Most of Princess Hope's elder siblings are this as well, but they grow out of it eventually.
- Broken Pedestal: Hopper initially looks up to Emperor Titus, but loses practically all of his respect and compassion for him when he learns of the true purpose of Titus's refugee camps.
- Card-Carrying Villain: Felina flat-out states that she has no good points.
- Cats Are Mean: Played straight with Felina and her band of ferals, but averted with Ace.
- Conscription: Pinkie institutes this after taking control of the Mūs village.
- Ear Notch: Hopper and Pinkie both have this due to them biting each other's ears near the start of the first book.
- The Emperor: Titus of Atlantia. He is later succeeded by Zucker.
- Empire with a Dark Secret: Atlantia is kept safe from the ferals due to a peace accord made between Emperor Titus and Queen Felina. However, what most of the population, and even Prince Zucker initially, are kept in the dark about is that the price of the accord is that the rodents from Atlantia's "refugee camps" are regularly offered as sacrifices to the ferals, under the guise of being sent to colonize the tunnels under Brooklyn.
- Even Evil Has Loved Ones: As cold as he is, Titus, deep down, does love his son. The reason he struck the peace accord with Felina was in exchange for her sparing his family, and in his final moments, he offers his life in exchange for Zucker's.
- Eye Scream: Cyclone the cat gets his eye impaled on an iron spike at the start of Mouseheart, earning him the nickname "Cyclops".
- Face–Heel Turn: Pup in Hopper's Destiny, though he switches back early on in the following book.
- Faking the Dead: Dodger faked his death at Cassius' hands so he could move above-ground, sire a litter, and return to the subways to take up the mantle of La Rocha.
- Fantastic Racism: Pinkie refuses to allow any non-mouse refugees to enter the Mūs village, reasoning that their larger size means they will consume more resources.
- From Nobody to Nightmare: Titus used to be a lowly commoner rat until he struck a peace accord with feral queen Felina, leaving the other rats indebted to him and allowing him to proclaim himself emperor.
- God Save Us from the Queen!: Felina is the queen of the ferals.
- The Good King: Zucker becomes this after assuming the throne following his father's death.
- Green-Eyed Monster: Pup begins to envy his older siblings for overshadowing him, driving him to attempt to kill Queen Felina by himself to prove his worth and, when that fails, vows vengeance against Hopper and his allies. He gets over this by the next book, though.
- Heel–Face Turn:
- Pinkie in Hopper's Destiny after discovering her father is alive.
- Pup early on in Return of the Forgotten, not that he was really evil to begin with.
- Large and in Charge: Titus is the emperor of Atlantia and practically towers over his subjects.
- The Load: Pup views himself as this.
- Mook Lieutenant: General Cassius, Titus' oldest friend and the leader of Atlantia's soldiers.
- My Greatest Failure: Firren considers not saving Devon's brother Ira to be hers.
- Not Quite Dead: Dodger.
- Police State: The Mūs village becomes this in Hopper's Destiny after Pinkie stages her coup and takes over.
- Railroad Tracks of Doom: How Felina meets her end.
- Rat King: Emperor Titus of Atlantia. His son Zucker later takes his place.
- Rebel Leader: Firren is the leader of the rangers seeking to overthrow Titus' evil regime.
- Redemption Equals Death: Titus allows himself to be devoured by Felina in exchange for her sparing Zucker.
- The Resenter: Pup in Hopper's Destiny. He begins to hate how much his elder siblings overshadow him, with Hopper being The Chosen One and Pinkie the new leader of the Mūs, and thus tries to prove his worth.
- Revenge: Devon's primary motivation in Return of the Forgotten.
- Revenge Before Reason: Devon is determined to kill Firren and her family because she didn't help save Ira while they were in the hunting grounds, leading to his death. However, as pointed out by other characters, Firren was just a child at the time and petrified due to being in such a terrifying situation, so he was expecting too much from someone so young.
- Revenge by Proxy: Devon schemes to get revenge on Firren for not saving his younger brother Ira from death by abducting and murdering her children.
- Tell Me About My Father: Hopper says this to Zucker regarding his father Dodger.
- Tyrant Takes the Helm: Pinkie after taking control of the Mūs village, quickly turning it into a Police State, ordering every able-bodied mouse be conscripted into her military, and refusing to allow Atlantian refugees be allowed to seek shelter. Luckily, Dodger manages to get her to come to her senses.
- Villain with Good Publicity: Titus is revered by his subjects due to his peace accord keeping them safe from the ferals. However, this all goes down the drain once they learn the truth of his deal with Felina.
- The Wise Prince: Prince Zucker, who later graduates to The Good King.
- You Dirty Rat!: Averted with the majority of the rats, but played straight with Titus and his soldiers.
- You Killed My Father:
- General Cassium murdered Hopper's father Dodger. Or so it seems.
- Zucker's grudge against Queen Felina is primarily motivated by her eating his mother, Queen Conseylea.
- Felina also killed Dodger's father Ebbets, in addition to his mother and siblings.
