Volo joins your camp as well if you do things right, but since bard isn't ready...
For the love of God stop calling Volo a bard, he isn't one, our character call him a bard only because he is forced to do bard's work at that moment. He is a travelling scholar and a weak wizard. Or are you really finding his singing inspiring?
And no, the fact that characters join our camp doesn't mean they will be our companions. Larian announced those characters long ago as "camp followers", who will provide some convenience inside the camp, maybe will join us for a certain mission, but won't be our companions. And they had it the same way in previous games.
