|rouen-cathedral-gargoyle by ShironekoEuro|
It is natural to have multiple versions of such a popular fable: In one scenario, St. Romanus purportedly subdued the creature using a crucifix and led the then docile beast back to town on a leash made from his priest’s robe. In another version St. Romanus captured the beast with the help of the only volunteer, a condemned man.
In both cases the monster was led back to Rouen and burned, but only partially. You see the head and neck, being tempered by its own fiery breath, could not be incinerated. Undaunted, the head of Gargouille was still utilized for protection and was promptly mounted on the wall of the newly built church to scare off evil spirits.
Since then, in commemoration of St. Romain, the Archbishops of Rouen were granted the right to set a prisoner free on the day that the reliquary of the saint was carried in procession.
The Roman Catholic Church, by then an influential entity, seizing this opportunity, utilized these images to convey certain ideas to the illiterate populous and also to convert pagans to Catholicism.