You can see in the dark and magical dark up to 60 feet, you cannot discern color

As an action, you transform yourself into your true demon form. When you use demon form, you cannot use any of your racial abilities except unarmored defense and darkvision. While in demon form your armor increases to max of 20 (provided by Race) and you have advantage in all of your melee weapon attacks but so does the enemy, at lvl 5 while in demon form you gain advantage to Strength and Constitution saving throw's and ability checks and disadvantage to dexterity and intelligence saving throw's and ability checks. You may use demon form = to half your proficiency bonus per day. Once used up, you must take a Long rest to regain all usage of feature. After using the demon form you suffer 1 point of exhaustion. If you use a short rest you do not re gain any of your other racial abilities and will gain another point of exhaustion until you take a second short rest to equal the same time as a long rest. You are a large creature when demon. The demon form may last a while but you must be able to leave your demon form, or every 1 hour you must make a WIS sav (DC=18) or will take insanity points of damage worth 1d10. If you fail 3 times, your character is no longer in control and attacks everything in sight no matter who.

 While you are not wearing any armor, your Armor Class equals 10 + your Dexterity modifier + your Constitution modifier. You can use a shield and still gain this benefit.

Your Constitution score increases by 2 and your Strength increases by 1.

Demons are immortal in the sense of not dying by natural causes, any deadly injury they might get that leads to they're "death" will simply send them back to hell.

Demons tend toward the evil alignment, however this is not always the case.

Demons vary widely in height and build, from barely 5 feet to well over 6 feet tall. Regardless of your position in that range, your size is Medium.

Your base walking speed is 30 feet.

You can speak, read, and write Common and Abyssal