I recently created a Chaos Genasi subrace that has origins in the elemental chaos. They are meant to have a small amount of power from each of the elemental planes. I made them to be flexible and able to play as most classes.
Where other Genasi are from one of the Elemental planes, you are from the Elemental Chaos, where all elements mingle.
Ability Score Increase: One of your ability scores (other than Constitution) increases by 1
Elemental Absorber: Your exposure to the Elemental Chaos has given you a limited ability to absorb elements. You can cast the Absorb Elements spell once, and you regain the ability to do so when you finish a long rest. Constitution is your spellcasting ability for this spell.
Survivor in the Chaos: Your time in the elemental chaos has made you skilled at adapting to any climate. You are naturally adapted to hot and cold climates, and have proficiency in the Survival skill.