Crimson Dynasty.

Crimson Sorcerers harness the ancient magic of blood and life essence. They twist and guide the flow of this quintessential energy as a hunger grows deep within them. They manipulate their power to infuse the vitality of others, or they can rip it away and steal it for themselves.
Crimson Dynasty can be acquired in a variety of ways. Some with this power were born with it. Others were infused with it through a dark ritual or grim event. There are those who discover it through lost secrets.
Consult the Crimson Origins table for a possible origin of your power.
There are a variety of ways you might have received the ability to harness your Crimson Dynasty to manipulate vitality and life essence. The Crimson Origins table offers suggestions of where your power comes from.

Level 1 Features:

Blood Well.

You hold a reserve of vital energy called your Blood Well, which you can use to empower your magic and fuel other powers from this subclass. When you deal damage or restore hit points to a creature, you can expend your Blood Well to add 1d8 to the total for one target.
You regain your expended Blood Well when you finish a long rest or when a creature takes 10 or more necrotic damage from you at one time.

Cursed Dynasty Spells.

You learn additional spells when you reach certain levels in this class, as shown on the Crimson Dynasty Spells table. Each of these spells counts as a sorcerer spell for you, but it doesn't count against the number of sorcerer spells you know.
Whenever you gain a sorcerer level, you can replace one spell you gained from this feature with another spell of the same level. The new spell must be a necromancy or a transmutation spell from the sorcerer, warlock, or wizard spell list.

Level 6 Feature:

Pool of Blood.

As a bonus action, you can expend your Blood Well to magically dissolve into a pool of blood, along with everything you're wearing or carrying, for 1 hour. The transformation ends early if you drop to 0 hit points or if you choose to end it (no action required).
While you are a pool of blood, you use your game statistics with the following changes.
-Your walking speed becomes 10 feet.
-You gain climbing and swimming speeds equal to your walking speed, and you can climb difficult surfaces, including along ceilings, without needing to make an ability check.
-You have resistance to bludgeoning, piercing, and slashing damage.
-You have immunity to the prone condition.
-You have advantage on Strength, Dexterity, and Constitution saving throws.
-You can pass through small holes, narrow openings, and even mere cracks.
-You can enter and occupy the space of another creature.
-You can't drop, use, or otherwise interact with anything you were carrying or holding.
-You can't talk, manipulate objects, attack, or cast spells.

Scarlet Vigour.

You have resistance to necrotic damage. In addition, when you finish a short rest, you can expend your Blood Well to reduce your level of exhaustion, if any, by 1.

Level 14 Feature:

Vital Siphoning.

You can feed on your own life essence to fuel your magic. As a bonus action, you can expend a Hit Die and choose one of the following benefits.
Blood Boil. You regain the use of your Blood Well.
Crimson Pulse. Expend your Blood Well to make the next Metamagic option you use this turn cost no sorcery point.

Level 18 Feature:

Sanguine Feast.

Your hunger for vital essence is unquenchable. As an action, you can unleash tendrils of blood that lash any creatures of your choice within 30 feet of you. A target must make a Constitution saving throw, taking 5d8 necrotic damage on a failed save, or half as much damage on a successful one. If your Blood Well is already expended when you use this action, the targets have disadvantage on the saving throw. If at least one creature takes damage from Sanguine Feast, you regain a number of hit points equal to the damage roll.
Once you use this feature, you can't do so again until you finish a long rest, unless you spend 5 sorcery points to use it again.