Using your undead nature, you may utilise the blood you have consumed to regenerate yourself. The number of charges you have of this ability equals your proficiency bonus, and regenerates after every short or long rest.

On your turn, you take a bonus action to expend a chosen number of charges to regenerate a number of d8 equal to the number of charges you spent.

Whenever you would have to make a death saving throw, you may instead use this ability, ending your turn, and restoring hit points. If you do die, and your body is not overly destroyed, you will get back up in 24 hours. However, being downed by a stake through the heart or a silver weapon prevents you from reviving using this ability.

When you take the attack action, you may replace one of your attacks with a bite from your fangs. It acts as a natural finesse melee weapon with which you are proficient. This attack automatically hits if the creature is restrained or incapacitated, and has advantage if the target is grappled.

You may use this ability a number of times equal to your proficiency bonus, and only once per turn. You regenerate uses on a long rest.

On hit, the target takes 1d6 piercing damage, plus 1d8 necrotic damage, plus weapon modifier, and provided it isn't a construct or undead, you regain 1 use of your undead regeneration, along with 1 additional use for every 10 total damage dealt by your bite. 
The damage inflicted by your bite increases at the following levels: 5th level (1d6 piercing + 2d8 necrotic), 10th level (1d6 piercing + 3d8 necrotic),  15th level (1d6 piercing + 4d8 necrotic).

At 1 week without consuming blood, you will become blood hungry, meaning your vampiric features will become more obvious, you will gain an extreme craving for blood, and your undead regeneration will no longer recharge on a short rest. 

If you go a full month without humanoid blood, you will become blood starved, your vampiric features will become extremely obvious, you will struggle to think of anything other than your hunger for blood, you will be completely unable to heal, and for every further month you remain blood starved, you gain one level of exhaustion until you are no longer blood starved. Drinking blood while blood-starved will only move you back to blood hungry. If you reach full exhaustion, instead of dying, you go into an indefinite coma until you are fed humanoid blood.

The amount of blood you need to drink is around 1 litre a week of fresh humanoid blood to starve off blood hunger. Non-fresh humanoid blood will require double the amount.

You may try to sate your blood with that of animals. If you drink 1 litre of animal blood every day, the time it takes to get blood hungry and blood starved is doubled.

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 discern colors in that darkness as shades of gray.

You gain Heroic Inspiration whenever you finish a Long Rest.

You gain proficiency in one skill of your choice.

You gain an Origin feat of your choice.