I can imagine the design process behind Alucard went something like this:
"Hey the fans wanted Alucard, lets brainstorm about his design."
"Hmm, let's play it straight and keep his origins the same."
"Nah that been done, we gotta do something bold and daring like we did with Gabriel."
"Hey I got it!"
"Alright shoot"
"What if we take Trevor, color his skin grey, use white out on his hair, color his eyes gold, color his long coat grey with gold markings, give his battle cross some downward curves and call it something dark and depressing and expose his manly chest. Oh and instead of spending money on getting another VA for him, we just have Madden do his voice too and we'll justify it by having Alucard and Trevor be the same person."
"............. Fucking. GENIUS!"