Well, okay. It sounds challenging, but it might work out.
That said, we have now created on organization of formidable threat capability. Your vampires will have their work cut out for them.
You'll probably want to concentrate your artwork on showing the principal characters.
I think you would need to go back a ways to establish the "blood feud" origins between the groups, too.
Perhaps, sensing a potential adversary, the cabal was behind some attempts to rid the world of vampires.
One way to begin might be in comparing the recruitment procedures of the two groups, and emphasizing how they differ.
Or perhaps have a chance run-in between two really old adversaries, who each had thought the other dead, and now have to renew their efforts to control the situation.
Have them run into each other, sounds pretty interesting.
Would be funny and somewhat odd to have them run across each other at someplace totally innocuous and odd for them to be at, like a shopping mall.
Or Staples office supply.