In Lords of Shadow's re-imagining of Castlevanian lore, Alucard is actually Trevor Belmont. Trevor is the son of Gabriel, the protagonist of the Lords of Shadow series. The last time we saw Trevor, he died in Lords of Shadow: Mirrors of Fate and was revived as a vampire after his father, Dracula, fed him his blood to try and prevent his death.
Alucard's grey skin and yellow eyes hints that he is starving himself for many years, refusing to partake in the delicacies of human blood, unlike his dear, old dad. After finding out what his dad had become, what he did to him and what he is doing now, it looks as though Alucard isn't happy.
We can't wait to finally play as Alucard once the Revelations DLC arrives for Castlevania: Lords of Shadow 2 on March 25.