Any ability score increased by one.

Gemini have an infinite lifespan. They are created and not born.

All dark Gemini are evil and chaotic evil. 

Gemini are about 4 feet tall. They have thin, lightweight bodies that weigh about 60 pounds. Your size is small

Your base walking speed is 30 feet.

You have a burrow speed of 20ft. To use this speed, you can’t be wearing medium or heavy armor.

Your body is a natural weapons, which you can use to make unarmed strikes. If you hit with them, you deal necrotic damage equal to 1d4 + your Strength modifier, instead of the bludgeoning damage normal for an unarmed strike.

You can  read, and write Common. You can only speak to other Gemini.

Your body emits a hazy smoke around you. This smoke can be amplified to 20ft if concentrating.

All attacks and actions you make are empowered by the darkness. If darkness is surrounding  the Gemini add an extra 1d4 if necrotic damage. If it’s movement based you can move an extra 5ft