Spoiler for Guessing about Issa:
I still haven't see the RAWs (damn my lack of time in general), but when it comes to Issa... well, is it possible that someone is doing a doppleganger of him? Highly unlikely, though...
... actually, a piece of the puzzle now makes sense (unfortunately): remember when Karua told Moka that their father would be so proud of her (or something along those lines...)? It seems that Karua probably knows their father quite well, as they seem to be in the same division (both are assassins). Still, we need some story here, since Issa seemed like a relatively decent guy in the flashbacks. Then again, everything may have changed with Alucard awakening and Akasha getting swallowed. Add in the vampire pride, and you have a rather nasty turn of events for Issa.
The only slight glimmer of hope we have here is that perhaps Issa is not as loyal to Gyokuro as she might otherwise think, since we've seen more than one Division Leader have plans of their own
Hm... yeah, i hate to say it, but it looks like Issa may very well be a very powerful antagonist for some time