I have some fics to recommend they are by Cosmic Compiler:
All three are Crossovers with Fate/Stay night, but at different points, the first one
Title: Castlevania Fate of the Dragon
Author: Cosmic Compiler
Genre: Action, Drama, Tragedy, Crossover (Castlevania)
Summary: A young Mathias Cronqvist meets Altria Pendragon, watch how he loves her and loses her, leading him to become the lord of the night, Lord Dracula.
Pairings: Mathias Cronqvist X Altria Pendragon.
Title: Castlevania Finale of the Dark Ballad
Author: Cosmic Compiler
Genre: Action, Drama, Tragedy, Crossover (Castlevania)
Summary: 1999 AC Julius Belmont participant of the third grail war summons Saber for the last battle against the forces of Darkness.
Pairings: Mathias Elizabeth Baltroy X Dracula, Altria Pendragon x Dracula.
Title: Castlevania Minuet of a Cursed Fate
Author: Cosmic Compiler
Genre: Action, Drama, Tragedy, Crossover (Castlevania)
Summary:Julius Belmont has laid Dracula to rest and has reincarnated onto Soma Cruz, but the forces of darkness do not wish to let the count to rest peace and so Soma is forced to summon Saber in a new HGW.
Pairings: Soma Cruz X Altria Pendragon, Shirou Emiya x ???.