Plaguebringer

Sorcerers of this archetype are perhaps best known as “plaguebringers”, since their very souls are marked by a merciless arcane disease or a similarly contagious curse. They live their lives with a second voice in their head, a parasite in their blood that has no other goal than to spread its infection to as many creatures as possible, not stopping until it has reached the very end of the cosmos and all worlds beyond that. For this reason, they are often shunned by society, where they are seen as bad omens and harbingers of death and woe. Plaguebringer sorcerers tend to hide under black cloaks when confronted by other people and usually wear masks to hide their identities. 
However, they all deal with their affliction differently. Some fight against the condition, attempting to suppress it, while others give in and embrace it, spreading its noxious influence. Few learn how to fully control the disease, but those that do will find its powers to be quite useful, employing them as an instrument to do good in the world and punish evil-doers, or to simply wreak havoc on civilization for their own sadistic desires.

Plaguebringer Sorcerer Quirks

At your option, you can pick or roll from the Plaguebringer Sorcerer Quirks table to create a quirk for your character.

d6	Quirk
1	Small, red dots appear and disappear periodically on your skin.
2	Your body always feels feverish to the touch.
3	Your eyes are of a sickly, yellowish colour.
4	People cough more often when they are talking to you.
5	You are unnaturally pale.
6	Mosquitoes and other blood-sucking insects are strangely attracted to you, which doesn’t bother you at all.

Plaguebearer’s Instinct

Starting at 1st level, you gain proficiency with scythes. For you, they have the stats of a glaive (see Player's Handbook). You also learn the Poison Spray cantrip.
Additionally, you can sense, locate and identify diseases, as if under the effects of a Detect Poison and Disease spell.

Contagion

At 6th level, whenever you deal damage to a creature with a spell that deals poison damage, you can force a number of creatures up to your charisma modifier within 30 feet of the initial target to make a constitution saving throw. You must spend one sorcery point for each creature you target. On a failed save, the creature suffers from the poisoned condition and takes poison damage equal to twice the spell’s level at the start of each of its turns. Creatures that are immune to diseases or the poisoned condition are immune to this effect. An afflicted creature can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success. This effect ends early if the afflicted creature is targeted by a spell that removes any disease and if said spell’s level is equal to or higher than that of the spell that was used to inflict this condition.

Miasma

At 14th level, you can cast Gaseous Form on yourself once per short rest without having to expend a spell slot or material components. While you’re in this form, you can cast Cloudkill without needing to provide any somatic, verbal or material components, but using up your available spell slots as normal. Casting Cloudkill this way doesn't break your concentration.

Parasite’s Blessing

At 18th level, whenever you would reduce a creature to 0 hit points using the attack action or with a damaging spell, you can reduce it to 1 hit point instead and regain hit points equal to the total damage the attack or spell would’ve dealt, up to twice your sorcerer level. You can use this ability an amount of times equal to half your charisma modifier per long rest, rounded down.