Rotting Soul
You were born evil. Your soul pulses with dark, sickly power and you relish watching the living breathe their last breath. You are a prodigy with necromantic magic; keeping yourself alive at all costs, and stealing the life from others. If you're powerful enough, you can even imbue corpses with a measure of your power and animate them. However, you are who you choose to be. It's not unheard of for sorcerers like you to reject their nature and aspire to heroism.
Withered Heart
When you choose this Sorcerous Origin at 1st level, you learn the false life spell. This does not count against spells known.
Whenever you regain Hit Points, you may target an enemy with 15 feet of you. That enemy must make a Constitution saving throw. If it fails, it loses Hit Points equal to the amount of Hit Points you gained.
Stolen Breath
Starting at 6th level, whenever an enemy within 15 feet of you dies, you regain 1 Sorcery Point and 1d4 Hit Points.
Gifted Heartbeat
At 14th level, you learn the animate dead spell and may cast it at will, and without consuming any spell slots. When casting this spell, you may expend a sorcery point to cast it at it's highest level, otherwise it is cast at it's lowest level.
Inherent Lich
At 18th level, if you die and your heart is not destroyed you gain a new body in 1d10 days; regaining all your Hit Points and becoming active again. If your heart is placed into the chest of a corpse (before rolling to determine the number of days), it is converted into your new body in 1d4 days instead.
Art credit: https://www.deviantart.com/saryth/art/Necromancer-299397947