
The more I think about it the more I feel like book 10 was designed to enforce a prevailing concept of the series: that of history being cyclic. Obviously this comes up a lot with the races that are ages old and also, more directly I'd even say, with the layers of the earth: with the geological aspect that betrays formed societies, old castles and awkward hills revealed to be ancient barrows. It also refers to warfare and the perpetual struggle of humans to make meaning while killing each other. Our worthiness to inherit...anything. Book 10 gives us the 'new' Bonehunter marines coming from the regulars - whose names I don't remember - but they play a big role in supporting Tavore in the final battle. I saw this as emblematic of the Bonehunters' own rise. That events like this are what bind the greatest fighting forces, like Blackdog and Raraku to the Bridgeburners (or whatnot). These soldiers could have their own 'story.' SE gives us them at the very end to enforce the concept that 'great heroes' exist before and after this series of events. This is just the story of some. There is more and not always with the people you know. Fiddler is done. Grub is just beginning. Etc.
So with this concept in place I'd like to offer Bottle as the next generations Quick Ben. He wet his feet halfway through the series and has just come into full power. There is more to be done in the world and as Bottle comes to eminance he will contribute greatly to such heroic battles and tales - but that is not the story of the Malazan Book of the Fallen. That is beyond, like Grub is beyond, but SE is too good to act as though the characters in the series are only relevant for what they do to the main plot. No, it extends much farther than that. So I see Bottle as an in-between. It might be many more years before Grub is Dassem- or Ganoes-esque but Bottle is one generation between Grub, Bellam Nom and Tavore, QB, Fiddler & the rest. He is a hero of that age, of the years to come when QB finally retires or goes nuts or whatever, Fid retires, and who knows what the rest do. So I don't think Bottle was forgotten... I just think he was groomed into an eminant power, but in the end, it wasn't his time yet. But through him you can see how the Malazan world will remain rolling forward... through history in cyclic fashion - the new replacing the old. If he'd reached his climax at the end of tCG, who would inherit Quick Ben's legacy after all?
Because we don't hear the end of some of these characters' stories, doesn't mean the stories end. Malazan history, in its entirety, is simply too huge for books.
That's one of the myriad reasons I love: I can fill some of that history in myself.