Holy crap! The TSoD has just wiggled its way into my story. The rumors of its resourcefulness are not underestimated.

But enough about that! Your CMinor needs to justify its place in your story. If its just hanging around....why? Is that what it does? What is its motivation to hang around? Nothing else to do? Wants to protect your MC? Wants to see your MC die and suffer? Biding its time so it may betray your Good MC to your Bad MC, or vice versa? A double double triple agent? It's all about motivation.

I had one character that was similar once. She seemed like she was just following these other 2 fugitives around, maybe she was one, too. But we didn't discover what she was about until the end of her story arc, and then she disappeared from the tale having served her purpose to move the story along. I have a tremendously long story where I have characters enter and leave on a regular basis, and not all from the icy grip of Death himself. In fact, some of the Minors don't even appear until 75% into the story. They just hadn't crossed paths with anyone being documented in the story yet.

So my point is: discover their motivation, and their backstory. If they are in the story, figure out how they got there. If the character is interesting, find a way to keep it in the story. If it's not interesting and serves no value, don't.