Some Masters and Servants might be that compatible. But you're missing the important part, mouse: command spells. If my Master were to turn traitor, willingly or otherwise... of course, I'd kill them with my own hands, but I'm sure you can imagine the consequences for any other Servant.

[ Part of her can't help but wonder, though — what if? What if the Master that called for her was someone worthy of standing alongside her; if not as a king, then at least as a friend? It's pointless to think about now, but Gray's words fill her with a sense of longing that she didn't think herself capable of feeling. One she angrily dismisses. ]

More importantly, a king is someone who stands alone. That's how it was for my father, and that's how it is for me. I can't... no, I won't rely on anyone but myself.