Do Devils leverage demons and vice versa?

Question

I'm running an adventure where the behind-the-curtain big bad is Baalzebul. According to 5e monster manual, Baalzebul is a lord of devils. Thus, I'm adding some more appropriate devils to flavor the encounters.

However, I'm wondering if there's any by-the-book notion of devils leveraging demons. From the 5e monster manual, it seems like devils and demons don't necessarily work together

Are there any D&D rules on whether demons and devils work together, or would summon each other? Material from other editions would be OK for filling in blanks if it doesn't contradict D&D 5e material.

Answer 1

Devils and Demons get along like a house on fire ...

... people screaming, running around, flailing, dying etc.

In accordance with their lawful alignment, devils obey even when they envy or dislike their superiors, knowing that their obedience will be rewarded. The hierarchy of the Nine Hells depends on this unswerving loyalty, without which that fiendish plane would become as anarchic as the Abyss. (Monster Manual).

Devils are the embodiment of evil: specifically the type of evil implemented by large bureaucracies. People can be tortured and made to suffer but only when a 37B form has been completed in triplicate and appropriately filed. Ok, not really, but they are the embodiment of organised evil. They therefore have a lot in common with Angels who are the embodiment of organised good, however, angels and devils do not work together.

Demons are the embodiment of chaos and evil- engines of destruction barely contained in monstrous form. Possessing no compassion, empathy, or mercy, they exist only to destroy. (Monster Manual)

People can be tortured but only if the demon wants to: and it always wants to. They are the embodiment of random evil. Demons and devils do not work together - indeed, demons and demons do not work together, they are too individualistic.

That is not to say that a particularly cunning and clever devil couldn't utilize demons in their plans but such circumstances would usually involve deceit rather than cooperation. Demons, of course, don't make plans.

Earlier editions of D&D specifically had demons and devils locked in an eternal Blood War, however, 5th edition has, as yet, not given us any information about it.

Answer 2

"Leveraging" is too vague a term because the answer is Yes and No.

Demons and devils prefer not to work together, generally, both because of strong alignment differences but also because a lot of previous D&D lore includes the Blood War where the demons and devils are actively fighting each other on the lower planes.

However, there are many exceptions to this general rule.

1. Compulsion. Most summoning spells are performed against the will of the summoned creature. Of course a devil might summon a demon to fight someone, especially if that someone has specific anti-devil/anti-law protections and loadout. Just like a human wizard might summon a demon to fight someone.
2. Individuals are exceptions to the rule, always. You get some smarter demons/devils that decide they need to work together for some specific goal. You probably have LG paladins and CG rangers in your PC party... It's not impossible to overcome these kinds of differences when there's tasty souls or whatever to gain.
3. Forced to by a situation... Held in an angel jail? Sure, let's work together to get out. Trapped on the Prime Material and you're the only other evil outsider in the zip code? Let's see what we can work out.

"Demons and devils don't get along" is like "orcs and elves don't get along" and "dragons care most about hoarding treasure"... These are fine bits of fortune cookie wisdom that are in general stereotype true, but have little to do with what the specific individuals in your specific plot and situation and world will do.

Answer 3

I think the main answer to this question is "it depends on campaign and DM". Back in the 3rd edition you had Blood War as others pointed out, and the general rule was that Devil and Demons were completely different beings that did not cooperate. That they were natural enemies, and even though both were evil, the nature of evil their represented was so radically different that they were natural enemies. In other editions, from 1st till 5th it kinda depended on world.

Personally I think that Devils and Demons are completely different type of an Evil. Think of a Devil as an evil politician that commits great evil, such as starting genocide, but follows certain rules and regulations to the letter of the law. While Demon would be something like a spree killer, kills for the pure pleasure of it.

Given that it is difficult for them to cooperate, but not impossible . The thing is that both Devils and Demons are in fact very smart beings. They don't just react they think, they plan, they make friends and enemies. While their thought process maybe completely different, they still might use one another to achieve their own gain. For instance in order to take over this city full of souls, a Pit Fiend may cooperate with Balor. However they are likely to fight each other after words.

Now personally in my campaign I take things on individual level, and so unless a being is of pure magic, they have an option. Therefore you could have non-evil Red Dragon, or a good Devil, given right circumstances. Just that such things are very rare, especially given that Hell/Abyss is itself an evil place, always corrupting everything that is within its reach. So being a good devil is not only against its very own nature, it also would need to fight of other Devils (who would see that as heresy) but also the world itself that keep trying to corrupt you. Yet it can and did happen.

So my answer is, do in your world what you think is right, and tells best story you can.