Father Geraldo is the Catholic priest for the parish of Kimmage in Rat. The good father is a fiery, somewhat eccentric man, and the immediate mentor and superior for Pius Flynn, who aspires to become a priest. Father Geraldo is mystified by the familiarity of Pius' surname (which the latter suggests is due to the fame of Erroll Flynn). Presiding over Sunday mass, the priest is not afraid to loudly call attention to anyone talking or canoodling during the service, and threatening to bounce them around.

Father Geraldo is also renowned for his skill at exorcisms, though he needs time to prepare. With a complicated kit which includes branding irons and other torturous implements, he's called to the Flynn house, to both give Last Rites to Hubert Flynn if needed and also to exorcise him, and possibly releasing him from his rodent state. The father frets over which to give first; if he performs the exorcism, the shock could kill Hubert, and he'd die without receiving the last rites, but if he gives the former first, then the devil would also receive last rites, which he is not entitled to. With much ceremony, Father Geraldo proceeds with the exorcism, though he notes that the refrigerator is a dangerous place to keep a devil. After waving his cross and cursing the "Babylonian bastard" and "Scarlet whore," Father Geraldo is shocked by the sudden manifestation of a naked Hubert, "a funny sort of devil."