I never really saw any hint of that kind of relationship between Dracula and Xander. In the comics, what I saw was a nobleman of the old (okay, ancient) school who lived by a certain standard, namely, "Cross me in any way, and I will scatter your various parts to the four winds. Likewise, those in my employ, so long as they remain loyal to me, are under my protection. Harm any one of them, and it is just as though you have crossed me." Dracula was by no stretch of the imagination a good man by our modern standards, but he never even pretended to live by those standards. He was, in the comics, at least, a predator who respected his prey, killing for food, for self defense, and to protect those under his care. In Season 5 of "Buffy," he was, at best, a parody of the "real" Dracula. Thankfully, that was corrected in Season 8.
I do feel, however, after saying all of that, that he and his manservant developed a real friendship during their year together, and I think that there would be an interesting story there if Joss ever decided to tell it. But romance wouldn't enter into it anywhere. But there would be a great opportunity for a male bonding scene with the Xan Man and the Big D sitting, late into the night, over more than a few bottles of fine vintage wine, or maybe something much stronger, sharing memories of Anya. That might, in fact, have been a large portion of the reason for Xander staying there in the first place.