The last tenant to rent a room in his head didn't quite hijack. It wouldn't shut up a lot of the time, mostly whispering at him to do things or offering its opinion, wanted or no. One time it did make him sleepwalk, though. Eventually, he was able to put up a privacy screen of sorts between it and himself, but that's a different animal, I'm guessing. 

Asking! Of course, makes perfect sense. The Captain has a few seconds at least, guess now's as good a time as any.