By living in the deepest darkest depths of hell they have adapted to being able to see in the dark. They can see infinitely in the dark. 

Depending on your demon level you receive a bonus in 2 abilities of your choosing. Level 1-3 add a +1 if level 4-5 add a +2

Demons are very cunning and manipulative, they have the ability to bend the will of others to do their bidding. You can take over the mind of a human or beast as long as you maintain concentration, if concentration is broken or are knocked unconscious the possession wears off. The target creature must make a DC wisdom saving throw of 15 to not be affected by the possession. If a demon of a lower level than you is within 60ft of view you can command it to do whatever you want if out of view or knocked unconscious the demon flies away or is desummoned.

There are many levels to hell some stronger or wiser than others. Depending on which level the demon came from it’s abilities can vary.

1St level

These are the weakest of the demons mostly used as slaves, or low level summons. They don’t have a lot of power so there strength is usually very low.

2nd level

Slightly stronger than the ones of the 1st level but they are very stupid and require a higher level demon to command them. 

3rd level 

one of the smarter of the demons they are able to act upon their own personal will. They have the ability to control other demons of a lower level.

4th level

One of the higher ranking demons they are either workers or scholars who have gone down the wrong path. They are smarter and stronger than most, they can control other demons of a lower level.

5th level

The strongest of all demons. They can fly 20ft faster than any of the other demons. Most lived as nobles or high social standing mortals who became corrupt with their own power. They are the greediest and hoard whatever they can. They can control a demon of any level.  

You share the abilities of one other race of your choosing 

Being from the depths of hell fire is a common element in the realm. You can manipulate fire at will. With the snap of your fingers You can set any creature ablaze. You can shape and control fire at will, you can move it in any direction you want. You do 1d6c plus your wisdom modifier of fire damage. You can cast this spell twice per day you may take a short or long rest to be able to reuse this ability once. The target must make a DC arcana saving throw of 14 to not be affected.

Demons fly through the darkness of hell with their large leathery wings, they can fly endlessly as long as there energy is sufficient. If your health is below half your base you are unable to fly at this point.