Refreshing yaoi among the same old stuff out there.I think they know each other, but the t...

Why do you think so?

Boss may have seen Professor as a killer and not realized that they are the same person yet, and Professor forgot because he lost his memory. So after Professor tried to stab him while he was still half-conscious from sleep, Boss instinctively knows how dangerous he is. That's why it seems like he's keeping his guard down and pretending to be weak around Professor, when everyone is afraid of him, to gain Professor's trust.