Sealed Horror

The Seal

Beginning when you choose this origin at 1st level, a terrifying powerful creature that has been sealed inside of your body for years has finally manifested its power. You choose the creature type of the sealed horror within you. You are a humanoid, but you count as a creature of that type for the purposes of spells and features which reveal your creature type. You can speak, read, and write the language associated with your sealed horror's creature type. Creature type Damage type Language aberration poison deep speech fiend fire abyssal or infernal ooze acid speak with oozes undead necrotic speak with sapient undead fey (unseelie) cold sylvan Additionally, when you cast a sorcerer spell that deals damage, you can choose to change its damage type to the damage type associated with your sealed horror.

Walking Death

Also at 1st level, when your consciousness slips away, you can let the horror within temporarily take over your body. When you are reduced to 0 hit points, your sealed horror wrenches control away from you, dragging you to safety. You can immediately move up to 30 feet without provoking opportunity attacks. You can choose to expend a spell slot of 1st level or higher, moving an additional 15 feet per level of the spell slot expended.

Monstrous Aegis

When you reach 6th level, you can use your bonus action to spend 1 sorcery point to gain resistance to the damage type associated with your horror and advantage on death saving throws for 1 hour.

One of Them

Also at 6th level, whenever you make a Charisma check when interacting with creatures of the same creature type as your horror's, your proficiency bonus is doubled if it applies to the check.

Support from Within

At 14th level, the horror within understands that its survival necessitates your survival. You gain your choice of one of the following features, depending on which represents your horror the best:
Supernatural Armor. Your AC is 21 unless it would be higher.
Toughened Skin. When you take damage, you can use your reaction to reduce the damage taken by an amount equal to your sorcerer level plus your Charisma modifier. You can use this feature a number of times equal to your Charisma modifier, and you regain all expended uses upon finishing a long rest.
Wall Runner. You are always under the effects of feather fall and spider climb spells, and your speed increases by 15 feet.

Broken Enmity

The horror within is no longer your prisoner. You have made a pact with it, and now you can call for the mightiest of its powers whenever you want to.   When you reach 18th level, you no longer age, can't be aged magically, and can't die of old age. Whenever you sleep, you are always aware of your surroundings thanks to the sealed horror keeping the watch.   Additionally, you learn your choice of either the imprisonment or seal spell, which counts as a sorcerer spell for you but doesn't count against the number of sorcerer spells you know. You can expend 10 sorcery points when casting your chosen spell to cast it without material components. When you cast the imprisonment spell this way, you must choose the Slumber option of imprisonment. When you are under the effects of the imprisonment spell, you can choose to end its effects on you at any moment, even when it is cast by another creature.   Finally, when you use your Monstrous Aegis feature, you also gain resistance to bludgeoning, piercing, and slashing damage for 1 hour.