Gruven was inept in almost every way - he was a poor leader, a bungling tactician, a useless hunter, and an all-out coward. The only things he had going for him were his incredible skills at lying, his ambition to be the Taggerung (which, without the nagging of his mother, he would not even have), and a slight amount of strength. Antigra originally named him Zann, which meant "Mighty One", but Sawney Rath made her change it to his late father's name, because Zann was part of the Taggerung's title by right.
Gruven and his rival Tagg got into a fight after the Taggerung led Gruven on a false trail when the pair were hunting a runaway; the stoat was nearly killed for his pains, and refused to thank Tagg for sparing his life until ordered to do so by his mother and the seer Grissoul.
After Tagg deserted the Juska, and Antigra killed Sawney Rath, Grissoul (influenced by Antigra) proclaimed Gruven the new leader. Leading (in the loosest sense of the word) a group of trackers, Gruven set out to find and kill Tagg. This would give him the right to call himself Taggerung, as the law was whoever killed the Taggerung assumed the title. On his trek, Gruven was constantly shown up by his band, who regarded him as a whiner and a pretender, especially the veteran fighters Eefera and Vallug Bowbeast. After the two in question deserted to find Tagg on their own, Gruven decided to go after them instead, not really wanting to run into Tagg anyway. On the way, he set a landslide down on Bodjev's Tribe of Pygmy Shrews, killing many of them. Unfortunately for him, Tagg was staying with the shrews - the otter came after Gruven, who panicked and fled for his life.
When he finally did track down Vallug and Eefera, Gruven was the one who was captured by the treacherous pair, once again displaying his own ineptitude. After Tagg reappeared on the scene, rushing out of Redwall Abbey to confront the vermin, Gruven escaped with the last member remaining of his troops. Gruven was the faster runner; he found some swamplands, and lured the crew member, named Rawback, into them. Gruven then escaped back to his camp, preparing a story of how he was the only survivor in the fight against Tagg, and that he had beheaded the otter.
When Gruven finally found his old tribe, he discovered that it had been taken over by a fox known as Ruggan Bor, who had slain his mother Antigra. Gruven concocted a series of lies to try and convince the new commander that he really had killed the Taggerung, leading Bor to the decision to march to the Abbey to ask the Redwallers if Gruven had truly done what he said. Upon arriving at the Abbey one morning, Ruggan asked the group on top of the wall if they had seen the deed done. Tagg, now named Deyna, had had his tattoos and Juska clothes and ornaments removed, and decided to tell the golden fox that Gruven had indeed killed the Taggerung.
Nimbalo the Slayer agreed loudly with Deyna that the Taggerung was dead, adding conviction to the story. Gruven was thrilled out of his mind at his luck, and in his ecstasy failed to realize his danger. Since Gruven had been proven the Taggerung, whoever killed him would be the new Taggerung. Ruggan Bor did just that, by beheading the unlucky stoat on the spot with his huge sabre and kicking his head into the ditch.