Your Constitution score increases by 1, and your Charisma score increases by 2.

Tieflings mature at the same rate as humans but live a few years longer.

Tieflings might not have an innate tendency toward evil, but many of them end up there. Evil or not, an independent nature inclines many tieflings toward a chaotic alignment.

Tieflings are about the same size and build as humans. Your size is Medium.

Your base walking speed is 30 feet.

Thanks to your ethereal heritage, you have superior vision in dark and dim conditions. You can see in dim light within 60 feet of you as if it were bright light, and in darkness as if it were dim light. You can’t discern color in darkness, only shades of gray.

Call of the Dusk.  Starting at 3rd level, you can use your action to unleash the evil energy within yourself, causing your eyes to turn red and two bat like, flightless wings to sprout from your back.
The instant you transform:
In combat: other creatures within 10 feet of you that can see you must each succeed on a Charisma saving throw (DC 8 + your proficiency bonus + your Charisma modifier) or become charmed by you until the end of your next turn.
Out of combat: Your charisma modifier is added to all your ability checks (CHA)

Your transformation lasts for 1 minute (5 minutes out of combat) or until you end it as a bonus action. During it, your nails become claws, gaining a melee attack: +4 to hit, reach 5 ft., one target, Hit: 1d6 + your dexterity modifier, slashing damage. 

Once you use this trait, you can't use it again until you finish a long rest.

You know the charm person cantrip. When you reach 3rd level, you can cast the sleep spell as a 2nd-level spell once with this trait and regain the ability to do so when you finish a long rest. When you reach 5th level, you can cast the alter self spell once with this trait and regain the ability to do so when you finish a long rest. Charisma is your spellcasting ability for these spells.

You can speak, read, and write Common and Infernal.