Sir Pellinore is Percival's father in the arthurian circle, so thats gotta be Ironside's true name. The dog is maybe the Questing Beast since thats the one thats always connected to their family. I assume hell lightly take cues from the graal quests since these had Percival as a protag early on, if he went with Tristan hed probably be "adapting" Tristan and Isolde instead, but Im curious in how hes going to differentiate Tristan from him since hes like a kid Meliodas in some ways