Is it possible for the Byzantine Empire/East Rome to not conquer Bagratunid Armenia and instead the two have good relations.
Is it possible for the Byzantine Empire/East Rome to not conquer Bagratunid Armenia and instead the two have good relations.
I don't know, the Armenians were really between a rock and a hard place with Byzantium and Persia, and could play both sides against each other pretty well at times (which doesn't help relations, because the Byzantines know they're being played). Remember that the Armenians and their lords were for the most part Monophysite, which differs drastically (from an early medieval perspective) from Orthodox Christianity. This is a time when emperors and patriarchs were deposed and lost their heads over whether to worship icons or not within Orthodoxy, let alone accepting or tolerating heretics.
Why not have Armenia be a Byzantine Vassal.I'd say it's unlikely, especially from the ninth century. After the collapse of the Abbasid Caliphate, the Byzantines didn't really have any serious enemies on any front (well, arguably Bulgaria, but only occasionally and not even Krum or Symeon seriously threatened Constantinople), and expansion is going to happen in all directions. The Armenian principalities are simply too tempting a target to ignore, and even under relatively weak Emperors they're going to get swallowed up at some point, as happened IOTL in the 1050s and 1060s.
So, in all, probably not. The best way to help Armenia avoid Byzantine conquest is to keep the Byzantines weak. But the best way to do that is to keep the Muslim world united, which means Armenia is likely to be conquered/vassalised at best by whoever holds power in Baghdad.
Why not have Armenia be a Byzantine Vassal.