Noxious Soul

Sometimes, when a being is bitten or otherwise has venom enter their veins, it may linger past it's outward affects, and should a being which has lingering venom produce a child, they may take on an affinity for venom or poisons. Though that is the primary way one has a venomous soul, it may also suggest a great anger or spite in a bloodline, or in one's parents. However they may come to fruition, a person with a magical affinity for toxins will usually have a very easy time getting along with venomous animals, and may even be treated like they are part of that animals species, but with control, they can become powerful commanders of toxin and venom.

Toxic Veins

Having already toxic blood coursing through your veins, you are immune to poison and the poisoned condition. You also know the poison spray cantrip, as well as ray of sickness, which you can cast an amount equal to your proficiency bonus without using a spell slot, you regain those uses on a short rest.

Specialty Posions

Starting at first level, whenever you cast a spell that deals poison damage, each creature affected by the damage must make a constitution save against your spell save DC or become poisoned. At 6th level, your attacks that deal poison damage ignore resistance and immunity to poison damage. At 14th level any creature that takes poison damage from a spell you cast must also make a constitution save against your spell save DC or become paralyzed for minutes equal to the level of the spell, they can remake the save at the end of their turn. 

Poisonous Attraction

At 6th level, if you would take poison damage, you can instead use your reaction to spend 2 sorcery points to gain temporary hit points equal to the damage. You may also take an action to spend a sorcery point to remove the poisoned, petrified, or paralyzed condition from a creature.

Venomous Reign

Starting at 14th level, you can use your action to summon a cloud of toxic rain, the cloud rains down in a 30 foot diameter circle, in a 120 foot range. The rain cloud is treated as if you were concentrating on it, and lasts until you drop concentration, you can use a bonus action to move the cloud up to 60 feet, as long as it remains within 120 feet of you. Once you summon the cloud, you may not do so again until you take a long rest. When summon this cloud, you can choose 1 effect, or spend up to sorcery points to choose extra effects equal to the number of sorcery points you spend:

• If a creature moves into or starts its turn within the rain, it must make a constitution saving throw against your spell save DC or become paralyzed until the rain stops.
• If a creature ends its turn within the rain, it must make a constitution saving throw against your spell save DC or become blinded until affected by a greater restoration or otherwise as powerful magic.
• If a creature moves more than 10 feet while within the rain, it must make a dexterity saving throw against your spell save DC or have its speed reduced by 10 feet until affected by a greater restoration or otherwise as powerful magic.
• If a creature move into or starts its turn in the rain, it must make a constitution saving throw against your spell save DC or take 6d6 poison damage which ignores resistance or immunity to poison damage, and become poisoned, on a success, the creature takes half damage.
• If a creature ends its turn in the rain it must make a constitution saving throw against you spell save DC or gain a level of exhaustion.

Basilisk Eyes

At 18th level, you can take an action to spend 6 sorcery points to funnel your toxic blood to your eyes, making them akin to the eyes of a basilisk. While your eyes are empowered, you may take a bonus action to choose a creature, that creature must make a constitution saving throw against your spell save DC, or begin to turn to stone, if a creature succeeds it takes 2d6 poison damage which ignores immunity and resistance to poison damage. A creature that has begun to turn to stone's speed is zero, and it cannot take reactions, if it takes both a bonus action and action on its turn, it has disadvantage on its next saving throw. At the end of a creature that has begun to turn to stone's turn, it must make a constitution saving throw against your spell save DC or gain one point of turning to stone, on a success the creature loses one point of turning to stone, if they had no points of turning to stone, they stop turning to stone. If a creature gains three points of turning to stone, it becomes petrified until affected by a greater restoration or otherwise as powerful magic. Your eyes remain empowered for one minute, it ends early if you are incapacitated or if you die.