Twenty years before the time of time of Fate/strange fake, Delmio was called by Bishop Dilo to where he was assigned in Spain. Having taken the orphaned Hansa Cervantes from the wilderness after Hansa's village was slaughtered by a Dead Apostle, Dilo brought him to an orphanage. Hansa showed an extremely high aptitude for martial arts, so Delmio, extremely proficient in kung fu and other martial arts, was the best candidate in Dilo's eyes to take care of Hansa and train him. Skeptical of the situation, Delmio asked Dilo why he didn't choose Risei Kotomine instead, but Dilo cites Risei's commitment to the an important task in Japan and Risei's own son.
Delmio realized Dilo's intent of having him raise Hansa, Dilo mentioning Delmio's desire for a capable successor. Deciding to try to scare Hansa into declining himself, he told him he could have a silver coin if he could "take it", launching it at great speed comparable to a bullet. Meaning for it to hit away from Hansa and scare him, he was shocked when Hansa easily grabbed it out of the air. Delmio accepted the situation after that, and became Hansa's foster father. He trained him in martial arts, Hansa later taking up a position as an Executor of the church.
As of the time of the True and False Holy Grail Wars, Delmio is stationed in a Las Vegas chapel built on top of a casino. All priests within distance of Snowfield are ordered to gather due to the Holy Grail War, and Hansa is chosen to go. As they discuss the situation, Delmio says any members within Snowfield istelf are too inexperienced. He says Hansa is the best choice due to their proximity, and if not him, then Delmio himself would be the next candidate. As he explains details, he realizes Hansa was not listening at all. They proceed to banter with each other, Demio mentioning that Hansa should get off his phone, and Hansa prepares to leave with his Quartet. Delmio launches a poker chip directly at Hansa, who effortlessly catches it and throws it back with the same speed. Delmio mentions he thought Hansa's skills may have declined from being so glued to his phone, to which Hansa smiles back and tells Delmio he could use some thrill as well.
Delmio is extremely proficient in martial arts. With just his hand, he can launch a poker chip or silver coin with bullet-like speed, enough to pierce wood.