We're open for interpretation on Astolfo in regards to voice and accent.

Astolfo, Class Name Rider of "Black", is the Rider-class Servant of Celenike Icecolle Yggdmillennia of the Black Faction in the Great Holy Grail War of Fate/Apocrypha. 

Astolfo is known in his legend for being eternally optimistic and completely lacking in sense, and he can be called "curiosity in human form."  He is a frightfully unparalleled blabbermouth, prone to speaking on and on until those involved lose all rationality. His conversations, through no ill intent on his part, have a way of meandering toward maximum social awkwardness.