Aberrations and evil outsiders: how do they get along?

[Kafana]

I realize this is more of a "lore" question, but I was wondering what are the interactions between abbies and devils? As far as I understood, aberrations are something like aliens, while outsiders are obviously from different planes. My question is: what records are there that talk about interactions between these two groups? Anything in the official adventures or the monster manuals?

Do beholders make deals with pit fiends? Do mindflayers employ succubi?

[Fouredged Sword]

Aberrations are called such because they are exactly what is says on the tin. They differ from the norm. Each type is a unique little snowflake in how they deal with others.

Devils on the otherhand, will deal with anything that they can get to follow rules.

Lets take some examples.

Mindflayers - Devils

Well, both don't trust the other. The flayers will attempt to control the devils and the devils will attempt to not be controlled. Failing that, if the Devil has something the flayers want and otherwise cannot get, they may be willing to deal. The flayers likely sell slaves to get what they want. That said, flayers are very self sufficient with little need for the services of a devil. The most likely area of cooperation is dealing with the Drow and their demon allies.

Beholders - Devils

Beholders think that they are the ultimate life and everything else, even other beholders, are lesser beings. Devils may be able to work in the short term by playing into this 'reality', but in the long term Beholders just don't play well with others.

Aboleths - Devils

Well, you run into the mind control issue again, but this time dialed up to 11. The devil is likely going to be working though proxies dealing the with the proxies of the aboleth. Both sides are paranoid and would have to enter a disadvantageous area to meet in person. That said, it could happen.

[Telonius]

"Aberration" is a pretty varied group. It runs the gamut from tentacled weirdos like the Grick, to shapechangers like the Phasm, to playable characters like the Elan (http://www.d20srd.org/srd/psionic/monsters/elan.htm). The most iconic ones are probably the Mind Flayers and Beholders, but even those have pretty vastly different goals from each other.

Mind Flayers might actually work well with Evil Outsiders, if they can find a situation where working together would be mutually beneficial. For example, the devils want to turn a town Lawful Evil, so they arrange for the Mind Flayer to live next door and demand victims every once in a while.