Raniero was a member of the Algarvian royal family and a cousin of Mezentio. Mezentio installed Raniero as the puppet King of Grelz when his forces occupied the duchy. Raniero's kingship was opposed by a Grelzer resistance movement but was also supported by an anti-Swemmel Grelzer army.

When Unkerlanter forces retook Grelz, Raniero was captured by Leudast. Semmmel personally oversaw Raniero's execution in a vat of boiling water. Raniero faced his impending horrible death with great courage, defying his captors to the last and in an act of bravado jumping himself into the boiling water rather than waiting to be pushed.

Hearing of Raniero's fate increased his cousin Mezentio's determination not to let himself fall alive into Unkerlanter hands.