It'd also explain how he knew the Tardis was capable of time travel. He's possibly seen or been in something similar before. Alternatively, he might be The Captain, but NOT an earlier version, who might not recognise Roier since they've both regenerated since they last saw each other.

I'm thinking that Cellbit might also be a Time Lord since you said humans look like them. And following that logic, it might not be out of the realm of possibility for him to be an "earlier" version of The Captain. That'd also be a reason why he was so upset the first time Roier died. Continued...

I have one or two theories. Never seen Dr. Who though so probably wrong lol.

I really liked it. Does Cellbit suspect that it's Roier at all? Also, is the bit where he "sees glass" one of the blood loss symptoms, or is it something else?

I loved it!