Riggu came from a line of wildcat pirates who took over Green Isle, home of a large tribe of otters. He built a fortress and ruled over the island, keeping the otters as slaves. He was the only true wildcat on the island, as his army was made up of less-aggressive feral cats, who kept the remaining free otters at bay.
Felis and his wife, Lady Kaltag , had two sons, the headstrong and bloodthirsty Pitru, and the weak and cowardly Jeefra. He both admired and hated Pitru for his brashness and determination in becoming the next warlord.
Once, when Riggu was taking his sons out for an initiation hunt, they caught a large osprey named Pandion. When both of his sons were too afraid to take it down alone, even though its beak was pinned shut with a barbed ball, Riggu stepped in and fought the osprey, in the process getting half of his face ripped off and letting the bird free. Later, after being tended to by healers, the furious warlord issued that all birds on the island be killed. From then on he wore a special helmet that covered his raw, maimed face, only taking it off when we wanted to intimidate someone.
Felis had a special hatred for the leader of the rebel otters, Leatho Shellhound, who was a Robin Hood-like figure, always befuddling the Catguards and plotting to overthrow Felis and free his fellow otters.
Around the time when Tiria, the prophecied High Rhulain savior of the otterclans arrived on the island, Riggu Felis finally captured Leatho, hanging him in a cage outside of his fortress to starve to death. When Tiria and her forces lead an assault on the fortress, Riggu's wife Kaltag, set fire to Leatho's cage, as well as the tower it hung from, as she believed that Leatho had killed her son Jeefra, when in fact Pitru himself had done it.
Riggu Felis ordering his troops out on the dock overlooking the fortress's lake, when he saw Pandion the osprey (who had been rescued by Tiria in Mossflower and had joined her force), flying the injured Leatho away from the fire. Riggu then hurled his war axe at Pandion, killing him. Tiria, who had kept the round barb that she took from Pandion's beak, used her sling and hurled the barb at Felis, sending it right through his forehead and deep into his brain.
The Catguards were then lead by Pitru, but he was eventually defeated and killed as well.