I think the definitions of what is and isn't a companion have become very blurred in NuWho, what with the introduction of companions' families and so on. I'd say River is a companion, simply because she is a supporting character who has by now accompanied the Doctor on more than one adventure. Mind you, I think even going back to the old series... I refuse to believe that Sara Kingdom, who while a pretty cool character (as far as I can make out from recons etc) features in one (1) story can be considered a companion whereas the Brigadier, who featured in practically every story of the Three run and made guest appearances with Four, Five and Seven (and in SJA), cannot.
They're a companion if you want them to be, I think I'm suggesting.
Hello Sweetie--- I'm back after several months if not years away. Unfortunately, my daughter has strayed from Dr. Who fandom when Eleven went away, and will not watch or seek out 13, Capaldi nor Moffet.
I have recently learned that River Song has shown up at least once in the latest Season of the 13th doctor, and so, it's a classic "Hello Sweetie" moment. Does anyone know which episode that is in? Series and episode would help me hunt it down to watch for myself. (No, we don't have BBC In America, so I'd have to talk someone into sharing it or find it on my own.)
Cheers!, Kirk G
"But that's just a fairy tale..." "Aren't we all?!" -Dr. River Song (circa 2009)