More later on this fascinating topic, but for now, I shall content myself with revealing
Pope, later Saint, Hilarius
Perhaps the most amusing of all Popes...were I elected I would struggle to resist becoming Hilarius II...
Perhaps more interestingly, there was a Latin poet of the same name, active in 1125 I beleive, who was thought to have been an Englishman due to one poem entitled "An English Boy", or something of the sort.
More generally, Hilarius and Felix both indicate levity and set the tale's light tone.