It's not that Nikola Tesla hates William Zimmerman, per se. It's more of a strong dislike really. Oh sod it; he really doesn't even dislike him that much. He just… wishes he were someone else.

See there are times when Will is piecing together the clues, working out a pattern, figuring out what's going to happen an instant before it does, there are times, when Will acts so much like James. So much like him that it makes that thing inside Nikola's chest that he long ago ceased to acknowledge break, just a little bit. For another should never where the expressions that once adorned the face of his best friend. Those belong to James, and James alone.

Tesla isn't sure if Magnus sees it. Knowing her, she probably chose him just for that reason. Hey, for all Tesla knows Will could really be an illegitimate grandchild of James', who Magnus has been watching throughout the years. All he knows is that she chose someone so much like her best friend that he wonders if it really wasn't just a cry for James to come home and stay with her forever. It's too late for that now.

Tesla fights, sometimes, with himself about the way he treats Will. Not that he can help it. The truth is, he's not acting consciously, as much as he is on pure animal instinct. As far as the vampire side of him is concerned Will is in interloper intruding into his family. Tesla is fairly certain that this will fade in time. Didn't he once feel the same way about Henry? (He thinks he did. Though admittedly the feeling was less profound with him to begin with.)

Tesla can only stand on the outside and watch this interloper wear James' expressions and fight at Magnus' side. At James' place at Magnus' side. People don't realize, Will always stands a little bit behind her, and to the right. Same place James always stood. The left side was, after Druitt's desertion, where Nikola himself always stood. Henry stands there now. Tesla sometimes wondered if that had some deeper psychological meaning, like, the right hand of peace and the left hand of war, or some other such nonsense. In the end he always decides that it doesn't matter. Not really.

Years ago, Magnus made some comment about the cost of their longevity. At the time Tesla hadn't understood it. He loved the fact that he was going to live forever. He was going to get to see the world change and grow, and expand around him. How many people get a chance like that? Now though, he does understand. The curse of living forever is watching everyone that you love fade into nothingness, until they are nothing more than a wisp of a memory.

He can never get James back. Not James. Not Nigel. And not, in a very real sense, Druitt. All that he can do is hold as tightly on to their memories as he can. That is why, as much as Druitt might wish Will were James, he's not going to let anything happen to him either. Will makes Tesla remember. And that's not something he's giving up for the world.