Which happens first, the future in SR2 (where the demons first appear) or the whole of BO2.
Also does anyone have a timeline of all the games combined?
You may wish to check this (Compliments of Blincoln and The Lost Worlds) (http://www.thelostworlds.net/LoK-Timeline2.HTML) for a basic idea of how the timeline is organized.
Please note that it was released with SR2 and does not contain Defiance information. From what we can piece together after playing Defiance, Raziel starts the game in BO-era Nosgoth, while Kain is still back in SR2-era Nosgoth (roughly 500 years before BO). The climax of Defiance transpires pretty close to the events of BO. (Moreso towards the later events of that game). BO2 transpires 400 years later. Throw in another millennium and a few centuries later and we experience the events of SR1.
That Reaver that Kain wields in Defiance was taken from the Sarafan Era. Eventually, Kain will have to return it to that time otherwise the timeline won't continue properly.
Kain doesn't have to return the reaver to that time, because Moebious was the one who put it in Avernus for Kain to find, so the reaver could be taken from any point in time and placed in another. The timeline would adapt arround the slight change if there is a paradox, otherwise the flow of history would continue and the reaver would always be there as it always had been there.