I’ve been lost the last couple chapters but I forget the plot lol (⊙…⊙ )
Basically, the doctor is trying to prove to Cain that he is the one they're looking for. Earlier in the story, Sid gave the compass to the other demon so he could kill the doctor, which meant Cain couldn't get treatment that he needs (but Sid already told Cain that he found the doctor dead, so now if the doctor says that its him, Cain would be sus). So in order to get Cain to question Sid's loyalty, the doctor pointed out that Sid currently doesn't have the compass on him.
He actually doesn't have it right now. Cain said in an earlier chapter that the only reason he gave it to him was because he trusts him (then he broke that trust by giving the compass away to the other guy). But the doctor knows Sid doesn't have the compass because the other demon found him and killed his clone with it. So the doctor is going to use it to advantage and get Cain to realize Sid betrayed him since he gave the item away. So hopefully Cain will realize that Sid is a backstabbing hoe and beat him up in the next chapter.
Aww that’s sad how he got treated like that and he thinks the director will do the same ┗( T﹏T )┛ but them ugly boys who was doing that need punched and beaten the shit often them (๑•ㅂ•)و✧