Sanguine Soul

Long ago, your family was inflicted with a powerful blood curse, making your family line barely any better than vampires. Food and drink no longer sustains you, only the vital essence of humanoids. 

Physical Manifestations 

D6	Physical Manifestation
1	Your skin is so pale that you look like a porcelain doll.
2	The whites of your eyes are entirely black and your pupils are blood red.
3	Your hair is bright crimson or you have red streaks running through it.
4	There are blood runes seared into your flesh in places of your choosing that pulse with power when concentrating on a spell.
5	Your veins glow bright red when casting spells.
6	You cry tears of blood.

Blood Aegis

The nature of your curse means that food and drink no longer sustain you, although you can imbibe them but gain no nutritional value. You must sustain yourself on the blood of humanoid creatures every 12 hours or become poisoned until you do. However, while fed in this manner you gain Blood Aegis and you add your constitution modifier to your AC while you aren't wearing armour or wielding a shield.

Vile Blood

At 1st level when you take this subclass, your blood is cursed and becomes rotted and foul. You have resistance to poison damage. In addition when you are hit by a bite attack, the attacker takes poison damage equal to your sorcerer level plus your constitution modifier (minimum 1).

Blood Magic

At 6th level, you have learned to use the cursed magic of your blood in lieu of any material components. When casting a spell with a material component, you can sacrifice a number of hit points equal to the spells level to bypass the need for any material components. In addition, when using this trait to cast a spell, you can choose to change its damage type to necrotic.

Sanguine Regeneration

At 14th level, your curse has progressed to where you gain a regeneration factor and resistance to necrotic damage. As long as you are not poisoned by not being fed, you can use a sorcery point to regenerate a number of hit points equal to your constitution modifier (minimum 1) plus your proficiency modifier as a bonus action on your turn. 

Master Hemomancer

At 18th level, you have gained reached a new height of mastery over blood. You gain immunity to poison and necrotic damage. When you use your Blood Magic trait to cast a spell, you no longer lose hitpoints to cast a spell. 
In addition you can spend 4 sorcery points to attempt to exsanguinate a creature you can see within range of you. The targeted creature must make a constitution saving throw against your spell DC taking 5d10 necrotic damage and healing you for a number of hit points equal to the necrotic damage dealt on a failed save, or half as much on a success.