"It's true that I used to hate the Fierce Dogs for their cruelty. I didn't like how they were trained to be the teeth and violence of the longpaws. That's how I'd known them before the Big Growl- as Longpaw Fangs. They're different now. They do not answer to anyone. When my Pack grew to include Leashed Dogs I saw how easily things fell apart between them. The Fierce Dogs stick together. I respect Blade. I admire her clear thinking and authority and the discipline of her Pack."
The Fierce Dogs, or Blade's Pack, is a Pack of Dobermans, most of them described as having dark, lean, bodies with pricked ears and pointed snouts led by Blade. They are credited as the Wild Pack's main nemesis and the arc's antagonist, hunting them down for most of the Original Series.
According to Lucky's knowledge of the city and Fierce Dogs, these type of dogs normally are guardians of longpaw homes and work-houses, "doing the bidding of longpaws with harsh voices and glowing light-beams and vicious sticks." 
The Fierce Dogs originally lived in a facility known as the Dog-Garden, where they were trained by their longpaw Masters. When the longpaw Masters maintained and controlled the Dog-Garden, prior to the Big Growl, they would drill the Fierce Dogs to be obedient and march around the Dog-Garden. The longpaw Masters always sounded angry and never spoke except in a harsh bark. They'd strike any dog to put them in their place - adult and pup alike.
Following the Big Growl, the Fierce Dogs began to actively pursue the Wild Pack to retrieve Storm and had no permanent territory to call home, thus being largely nomadic. In The Empty City, the Fierce Dogs' territory was a training facility for the Fierce Dogs, although abandoned by the longpaws and temporarily self-sufficient. The dogs had automatic food bowls that dispensed pellets of food. In the next book of The Endless Lake, the pack formed a base in the longpaw town by the ocean.In the Storm of Dogs, the Fierce Dogs made their base in a cave. It is not known what their territory would be located following the Storm of Dogs battle and Blade's demise.
Blade, Mace and Dagger find Bella, Alfie and Daisy eating their food, while Lucky is hidden, watching in secret. Alfie and Daisy do the best thing, going into a submissive posture, but Bella is stubborn, and will not back down. When Bella finally backs down, they take the three dogs prisoner. Lucky tries to figure out how to help his friends, and over hears Blade talking with Mace and Dagger about killing them. In an almost suicidal attempt, he insults Blade and her gang, calling them stupid and crazy in hopes of creating a distraction. When he insults their bloodlines, they chase him. Lucky is cornered, but another dog of Blade's gang suddenly says that the prisoners were gone. Lucky attacks Blade, and escapes. Blade and her gang are frustrated, and too furious to notice where Lucky ran off to.
Blade and her pack come into the Wild Pack's territory, accusing them of stealing her pups. She orders her pack to attack, and demands Alpha for her pups. She attacks Daisy, nearly killing her, but Alpha stops her and returns her claimed pups: Grunt, Lick, and Wiggle back to her.
Lick later returns to the Wild Pack, informing them on how Blade kept repeating how they were not her pups. She kills Wiggle, and is about to kill Grunt, but he is spared when he tells her of his loyalty. Blade proceeds to kill Lick next, but fog rolls in, allowing Lick to escape.
One of Blade's Pack members, Axe, is captured by longpaws and held against his will, forced to undergo experimentation with strange water given by the longpaws. He is released by the Wild Pack and they urge him to return to his Pack. However, he refuses to do so until he exacts his revenge on his captors. The Wild Pack members retreat, but not before seeing him shot. His fate is unknown.
Fang spies on the pack, and the Fierce Dogs form a plan to kidnap Lucky, allowing Blade to get Storm in her paws. According to the plan, Lucky gets kidnapped, and as predicted, Sweet, Bella, and Storm come to save him. The Wild Dogs are trapped and Fang is killed. Thanks to a small Growl, the dogs escape.
The Wild Pack forms a plan where Lucky convinces Blade to come fight Storm by the river. The plan backfires when Whine tells Blade the plan, so Sweet leads a giantfur to attack the Fierce Dogs on the way to the battle. Many Fierce Dogs are lost during their struggle against the giantfur. During the Storm of Dogs, the Wild Pack defeats the Fierce Dogs, with Storm killing Blade.