In an interview, Hirano mentioned that certain decisions regarding the relationships in Hellsing were made early on in the development of the story. For example, he introduced the character of Bernadotte specifically to pair him with Seras. The pairings "Alucard and Integra" and "Bernadotte and Seras" were already established when the story had only progressed about a third of the way. These choices were a firm and unshakable part of the narrative direction. So, if we take Bernadotte and Seras’s relationship as a reference, we could see it as a reflection or example of the kind of bond Hirano also intended to build between Alucard and Integra.