Jaggedtooth is one of the warriors that Tigerstar trusts the most. After Blackfoot and Darkstripe kill Stonefur, he is seen guarding the prison in which TigerClan is holding Mistyfoot, Featherpaw and Stormpaw captive. Ravenpaw, a loner that is visiting ThunderClan, tricks him into thinking that he is a RiverClan, now TigerClan, warrior with a message from Tigerstar; that he wants to see Jaggedtooth right away, and he sent Ravenpaw to take over guarding the prisoners. Though Jaggedtooth does not recognize Ravenpaw, he believes him and leaves, allowing Firestar, Graystripe, and Ravenpaw to rescue Mistyfoot, Featherpaw, and Stormpaw.
When Tigerstar is killed by Scourge, Jaggedtooth goes to join BloodClan, the group of rogues lead by the murderous cat. Boulder, another ShadowClan cat, says that he would love to get his claws on Jaggedtooth.
During the LionClan versus BloodClan battle, Jaggedtooth attacks Bramblepaw, a ThunderClan apprentice, but Tawnypaw, one of ShadowClan's apprentices, yowls at him to leave her brother alone, and attacks him. Jaggedtooth is seen fleeing Fourtrees with the apprentices hard on his paws.
Snag is one of the rogues that participated in Tigerclaw's battle against ThunderClan. He, along with the other rogues, are actually terrified to see Tigerclaw risen from the dead, despite the cats saying otherwise. Snag watches the encounter with wary eyes, lingering at the back of the den. As Tigerclaw gets the cats organized once again, Snag and Tangleburr are said to be the least wounded. He volunteers to hunt if Tigerclaw wishes and goes out to hunt with the she-cat. The next day when Tigerclaw has awoken, Snag appears shaking dust from his pelt. He asks if Tigerclaw had spotted a patrol, although the latter responds in the negative, saying it was too early. Snag disappears back into the brambles.The group heads for the ShadowClan border, and he is shown a Twoleg hedge that borders ShadowClan territory. Blackfoot explains he discovered a hole when he was an apprentice and got through once. Tangleburr asks who knows what's on the other side, and Snag says there are just more trees. He asks Tangleburr what she was imagining, a group of badgers and foxes waiting to attack. They find a den to rest in, and Snag announces he found a puddle that tastes fresh enough. They settle to the new area and Tigerclaw declares they will start battle training.
Three sunrises later, Tigerclaw tells Snag to not be afraid to use his weight against his enemy as if they cannot breath they cannot fight. He nudges Snag forward so he is hanging over Clawface. Stumpytail points out that he will be easy to knock out now, since his balancing on three paws. Tigerclaw agrees and lets them battle it out. Snag swipes down at Clawface but at the same time is hit in the haunches by Stumpytail. Snag lurches sideways with a hiss and is pinned onto the ground by the two toms. The group starts hunting for ShadowClan and Snag knocks a squirrel out of a tree with a blow. The two days since the battle training Snag has become more confident of using his weight in battle. They bring the prey to the camp with Snag at the back, flaring his nostrils at the scent of sick cats. He is reluctant to go in but follows the group. He hears the stories from ShadowClan and is sympathetic, vowing catch all the squirrels in the forest for the Clan. After some time gaining the trust of ShadowClan, Snag asks Tigerclaw what he said to Runningnose. Tigerclaw explains that the group will give their upmost support. Snag mentions that the Clan will need a great deal of support because of their failing leadership. Tigerclaw promises they will be repaid for it, and Snag meows good.
Tigerclaw is put in charge of patrols, so he orders Blackfoot, Snag and Mowgli to take a warrior and an apprentice and to go through basic attacks and defensive moves. He explains they'll join up for a mock battle later. All three cats nod in understanding. The forest is full of sound as the three cats test the Clan on their skills. At the end of the day, Runningnose invites all of the group back into the Clan, and Snag and Mowgli stand at the edge of the crowd, unsure what to do. Tigerclaw asks to give them warrior names, and he performs the warrior ceremony. Snag is renamed Jaggedtooth and Mowgli is renamed Nightwhisper. Tigerclaw mentions that StarClan honors Jaggedtooth's strength and fighting skills. The Clan cheers their names and the new warriors lift their heads proudly. Days later, Jaggedtooth tells Tigerclaw Runningnose should choose him as leader. He asks Tigerclaw why he didn't tell the medicine cat that and help make a decision. Tigerclaw claims he cannot determine the will of StarClan. Jaggedtooth says he doesn't believe in StarClan, and asks if that makes things easier. Tigerclaw holds his gaze then nods. He says Jaggedtooth has been a good friend to him, he will never forget that. Jaggedtooth nods back and says he knows.
Runningnose finds a claw that gives shadows like tiger stripes, and declares Tigerclaw leader of ShadowClan. Jaggedtooth's eyes gleam as he limps to Tigerclaw, blood coming from where a claw was ripped out. Tigerclaw glances at the injury and comments he took a big risk to see if it would work. Jaggedtooth lashes his tail and tells him it paid off and he can thank him later. Tigerclaw jumps onto the large rock and looks down at his Clanmates, noting Nightwhisper and Jaggedtooth are former strays and will be loyal to him to their last breath. Despite Jaggedtooth's great act of loyalty, Tigerclaw decides to name Blackfoot as his new deputy instead, to show Jaggedtooth that Tigerclaw owes him nothing.
He is with his apprentice, Rowanpaw, on a patrol with Tigerstar. When Tigerstar asks Rowanpaw what he can scent, he replies he can smell fox. The leader tells Jaggedtooth that he has trained his apprentice well, and Jaggedtooth thanks him. The next day, the three are out on patrol again. Rowanpaw says he can smell it again, and Jaggedtooth agrees, saying it is fresh, but faint. He and his apprentice attempt to attack Sasha when she reveals herself, but Tigerstar sends them back to camp.
When Sasha comes to the ShadowClan camp, Russetfur explains to her that she, Blackfoot, Boulder, and Jaggedtooth had all been rogues once, so Sasha would feel comfortable among the ShadowClan cats.
Snag, Mowgli, do you promise to uphold the warrior code and protect and defend this Clan, even at the cost of your lives?
I do, Tigerclaw.
Then by the powers of StarClan I give you your warrior names. Snag, from this moment you will be known as Jaggedtooth. StarClan honors your strength and your fighting skills, and we welcome you as a full warrior of ShadowClan.