In 2013 I postulated that the Malakim of the In Nomine universe could join the armies of hell. They would not fall, the choir is still resistant to that particular fate. However, should a Malakite decide that heaven is the true evil, they would have no choice but to abandon it. The only real challenge would be finding a new Superior willing to craft a heart so that they could still act on earth.
The seven deadly sins would hold a particular appeal to the Dark Virtues, seeing as their Words run directly counter to the false morality of heaven (or at least what the apostate angel would see as heaven’s false morality). Similarly, each of the lords of sin sees a kind of virtue within their own domain, and so would be more likely to accept one of the Dark Malakim than their peers.