Would you be okay with having Steve be acquaintances/friends of Ciel's parents, since they're from an ancient line of Hunters? Maybe Steve has worked with them on a case or two in the past, if you're okay with that? Or they can be closer friends/comrades, if you prefer. I plan on playing it so that it seemed like Ciel died when his parents did, so no one's actually looking for him but Steve would probably recognize him if we go this route. Mucho drama!
Not going to lie, I'm also tickled by the idea of a younger, teeny child Ciel having a mild case of hero worship for Steve, being all awed by the vampire hunter his parents worked with. Would that be something you're interested in?