Cursed Soul.

Sorcery often comes from high places. Mortals who mingle with the divine, the draconic, or the extraplanar, giving birth to children blessed with innate magical talents that can be honed to the highest degree of arcane expertise. Cursed sorcerers are the exception to this rule.
Sometimes an individual is afflicted with a curse so great that it imbues the victim with magic of their own, even if this magic comes at a great cost. Cursed sorcerers, called “maledicts” in fearful whispers by more common arcane practitioners, derive their magic from the curse that has been placed on them.
Maledictdom is seen as a magical ailment in the arcane community, an unhappy byproduct of evil magic being forced on someone against their will, with the express purpose of hurting them. Most maledicts share one common goal -- to end their curse -- but there is always the odd one who decides to embrace their bane and see it instead as a boon. To them, their curse is a magical double-edged sword. It can hurt them, but it can also hurt others... including the one who put the curse on the maledict in the first place.

Level 1 Features:

Curse.

As a Cursed Soul sorcerer, you have been inflicted with a curse that is the source of your sorcerous magic. Talk with your GM to outline the specifics of this curse and how it affects your character. You may choose to have the curse actually negatively affect your character mechanically, or leave it only for flavour.

Cursed Soul Spells.

Starting at 1st level, you learn an additional spell when you reach certain levels in this class, as shown in the Cursed Soul Spells table. The spell counts as a sorcerer spell for you, but it doesn't count against the number of ranger spells you know.

Cursed One.

When you choose this origin at 1st level, you have been inflicted with a curse that has permanently changed you intrinsically. Much like a curse placed on a magic item, your curse cannot be dispelled through common curse-breaking methods such as the spells Remove Curse or Greater Restoration.
You can use the power of your curse to power up your magic at the cost of your own vitality.
You can sacrifice hit points instead of sorcery points to use one of your metamagic options. One sorcery point corresponds to a number of hit points equal to half your sorcerer level, rounded up. You cannot sacrifice temporary hit points in order to use this feature.

Level 6 Feature:

Magic Maledict.

Beginning at 6th level, you can draw on the vitality of your foes instead of your own to power up your magic. If you have dealt damage to a creature during your last turn without using a metamagic option, you may use that damage instead of your own hit points to use a metamagic option during your current turn.
If you are using another creature’s hit points instead of your own, one sorcery point corresponds to an amount of hit points equal to your sorcerer level. You cannot use more than one metamagic option per turn using another creature’s hit points other than your own, and you must use the damage dealt to a creature during your previous turn.
Additionally, as a bonus action, you can use sorcery points to heal yourself for a number of hit points equal to half your sorcerer level per sorcery point used. You can do this immediately after falling unconscious as a free action.

Level 14 Feature:

Maliferous Casting.

At 14th level, your control over the curse that ails you allows you to transcend the limits of magic and metamagic. You can sacrifice a number of your own hit points equal to your sorcerer level, or a number of another creature’s hit points equal to double your sorcerer level, provided you have inflicted damage to that creature in your last turn for a number of hit points equal or greater to your sorcerer level as outlined in your Magic Maledict feature, to use a metamagic option you do not have access to. You cannot sacrifice temporary hit points in order to use this feature.
Additionally, you can sacrifice a number of hit points equal to your sorcerer level to cast a spell from the sorcerer or the warlock spell list you do not know. When you do so, you must also spend a spell slot of the corresponding level to the spell you wish to cast. You cannot sacrifice temporary hit points in order to use this feature.

Level 18 Feature:

Malefice.

At 18th level, as an action, you unleash the curse that has afflicted you onto others in a burst of dark magic. Select a number of creatures up to your proficiency bonus within 30 feet of you. The affected creatures are afflicted with the following effects:
-The affected creatures are under the spell Bestow Curse. You choose the nature of the curse when you use this feature.
-The affected creatures have disadvantage on their next attack roll or saving throw.
Additionally, the momentary release of the curse reinvigorates you and your magic. As part of the same action, you can cast a spell, on which you can use a metamagic option without expending sorcery points or sacrificing hit points.
Once you use this action, you can’t use it again until you finish a long rest, unless you spend 7 sorcery points to use it again.