Rhydderch

Rhydderch is a title synonymous for "leader" or "gargoyle leader" in 10th Century Scotland.

Robbie, King Culen, and even Wyvern the dragon used it when addressing or referring to Mentor. ("The Draw", "The Promise", "The Dream")

Real World Background

"Rhydderch" was a name borne by many northern British kings in the early Middle Ages. Among them was a King Rhydderch of Strathclyde, who slew Culen in 971, after Culen abducted his daughter.