Riggu Felis was a wildcat warlord who ruled on Green Isle and lived in a huge wooden fortress. He had a wife, Lady Kaltag, and two sons, Jeefra and Pitru. He was supported by an army of feral cats, who kept the native otters of the area as slaves. His life-long aide was the pine marten Atunra.
In battle with the great osprey Pandion Piketalon, Riggu had part of his face torn away by the bird's talons, leaving exposed bone and fangs beneath. After this major injury, Riggu was forced to wear a half-mask made of chainmail, disguising this grotesque wound. Though he managed to stick a star-shaped iron barb into Pandion's mouth, Riggu did not forget what the hawk did to him that day, and had his eye on revenge. He was also angry at his sons for failing to kill the bird.
Returning to the fortress, Riggu encountered trouble several times with Leatho Shellhound, a rebellious otter who led his fellow otters in several battles. In one, Riggu's son Jeefra appeared to drown, but in reality he had been killed by his brother Pitru. Through a series of strategic battles, Riggu eventually gained the upper paw and captured Leatho, throwing the otter into a high cage in his fortress.
Eventually Leatho escaped the cage with the help of Pandion, but soon after his new hiding place was set ablaze by Lady Kaltag, driven mad at the death of her son. Pandion and Brantalis Skyfurrow, another bird, were sent to rescue him by Tiria Wildlough.
They carried Leatho down but Riggu, fighting a battle with the otters below, recognized Pandion and threw his axe at him. Pandion fell to the ground, dead. Tiria, who had sworn to pay back the beast who put the iron barb in Pandion's mouth with his own weapon, loaded the iron star onto her sling and fired it straight at Riggu. It hit him dead-center between the eyes. He died with the star embedded in his brain, falling headfirst off the pier into the lake. It was later mentioned that his body was thrown onto the the burning remains of the fortress along with his catguards.
- It is worth noting that he is the only warlord to fulfill his revenge.
- "Felis" is the word for the genus of wildcats.
- On the back of the FireBird Fantasy edition of High Rhulain, the name Riggu Felis has been mispelled as Riggu Felisand.