How do you run NPCs in combat?
So in my group, we had to bring an NPC with grace and a blasphemy into the sin's domain to perform the Nail of Abel ritual and summon the sin to fight. Consequently, that also meant that npc was there in the fight with us.
Now in CAIN, since combats run based on actions from the players followed by reactions from the enemies, it didn't really feel like there was a good place for the npc to fit in.
One thing we could have done was just treat the npc like a player, letting them have their own action and concequent reaction in the combat scene. In retrospect, this may have been the better option, but I think at the time we were worried about turning the npc into a dmpc. I also think the mechanic of getting to choose who gets to act next would have caused the npc to get shafted and never picked to go. Plus an objectively weaker npc acting instead of us could have felt more punishing than useful, as any of his turns would have been weaker (yet still causing concequences) compared to one of our own turns.
What my admin ACTUALLY did for us was declare that on any risk roll of 6, the fight was going so well in our favour that the npc would get a chance to influence the battlefield on those positive outcomes. (There's actually more, I think on 6's the admin actually decided to let the npc act INSTEAD of the sin, not just in addition to the sin's reaction. I definitely think was WAY too strong, but maybe without that one detail it wouldn't have been as bad)
Here's the problem we ran into though: we rolled WAY too many 6's on the risk die that session. Our npc was throwing in an extra action after almost everybody's real action, and the sin was unable to fight back. We absolutely clobbered the sin with only one player getting injured, at all. I mean, I recognize that at the end of the day, we got VERY lucky, and with that many 6's rolled, we were probably going to clobber it no matter what... but it honestly just felt like that sin did not get the opportunity to fight back at all.
So how would you run npcs in your game? Would they just get a turn like the players do or could incorporating the npc into the risk die work as long as we tone it down and dont get insanely lucky? Or is there a different way this should be done?