Like all sorcerers, your magic is in your blood. Unlike other sorcerers, instead of embracing a heritage, you embrace the power inherent in blood itself, whether it be your blood or the blood of others. The fact that you can utilise another creature's life essence to power your own spells gives others pause to trust you, as killing for you is empowering. When you're a walking, talking, power source, you tend not to appreciate being treated as such by those around you.

Blood Font

At 1st level, whenever you kill a creature that is not a construct, elemental, ooze or plant, you gain 1 hit point per level you have gained in this class, which can be used either to heal yourself or as a source of temporary hit points. While you have temporary hit points from this feature, you also have resistance to necrotic and poison damage.

Blood Magic

Starting at 6th level, you can use your own blood as a means to gain sorcery points. As an action, you can cause yourself 3 hit points worth of damage for every sorcery point you wish to gain. These hit points cannot come from temporary hit points and this damage to you cannot be reduced or prevented in any way.

Blood Clot

At 14th level, as a bonus action you can expend the total current value of any temporary hit points you have gained from your Blood Font feature as an equal amount of necrotic damage added to one damage roll of a spell you cast.

Bloodborne

Beginning at 18th level, you can inhabit the physical form of another humanoid creature by transferring your life essence, within your blood, to another's body. For all intents and purposes, your body is left behind and is considered destroyed. To inhabit a creature, it must be reduced to 0 hit points but not be dead. Inhabiting the creature forces its own blood out of its body, and the person who once inhabited that body is considered deceased. You enact this feature by spending an action to touch the creature.

From that point on, you gain the physical characteristics of the creature but not any magical abilities or knowledge. Your mental ability scores remain the same but your physical ability scores are replaced by that of the creature you inhabit. You treat the new physical form as if it was your own, with the exception that you can be expelled by the dismissal effect of a dispel evil and good spell. If you fail the saving throw against this dismissal, you are instantly slain.