"But you have to satisfy the monster. The monster has tended to you for longer than anyone or anything else."

It is claimed that those who choose the Way of the Fabulist are marked- or perhaps stained- from a young age, tied to this path like fate. They grow and curl around their future and before they can even realize; Suffocate it. For whatever reason, perhaps in a desperate attempt to save your life, a misplaced lie or half truth rang a little too much. The gods never wanted to save you, instead, they pitied you; now cursing you to live forever knowing what you have said and done, a twisted punishment for praying to survive. As a result, you are tainted with this pity, with these marks of good and bad, and you must balance them or else be eaten alive.

Mixed Blessing

Starting at 3rd level, your markings begin to work with you rather than against you. As an expression of these markings along your body, your nondominant arm becomes darkened, plagued by a mark of sin, by a mark of your past and emotions and grows into a manifestation of fear and hatred and all that is bad. While your dominant arm cultivates a sense of wisdom and pride, gained from your years studying and traveling as a monk. On one hand, you host disgusting creatures born of hatred, including blowflies, centipedes, snakes, and more writhing and waiting for an instance to appear, occasionally bursting out and attempting to consume whatever lay near. While on the other, you have an arsenal of feats and glory awaiting your command to demonstrate utter and complete prowess.

Non-dominant: You gain advantage on checks made to grapple enemies. You may also attempt to grapple an enemy who is 10 feet away from you, pulling them 5 feet closer on a success and you may choose to use your Dexterity (acrobatics) skill rather than Strength (athletics). 

Additionally, whenever a creature starts its turn grappled by you, it must succeed on a Constitution saving throw against your Ki save DC, or take 1d4 poison and 1d4 necrotic damage. This die improves as your Martial Arts die increases (e.g it will be 1d6 poison and 1d6 necrotic at 5th level).

Dominant: You gain the ability to use bard cantrips for the time being, and as you grow and your marking manifests, you'll progress into being able to use level one spells from the bard list and more. Patience is key. 

Catch 22

At 6th level your markings spread along your body, providing you with unearthly hardiness. Whenever a creature takes damage from your Mixed Blessing features, you gain that many temporary hit points for 1 minute. As a result, you have to feed your nondominant arm to keep it more under control; and it's on a strict carnivore diet.

However, you're now able to use level one and some second/third level spells from the bard spell list, roll at advantage when grappling, carrying things, and the weight you're attempting to push, drag, or lift, and gain partial dark vision in one eye and are unable to be blinded in the other, from the respective sides.

Good & Bad

Beginning at 11th level, the markings have spread to your legs. While you have an enemy grappled, you may move them with no penalty to your movement. Along with this, you can now use second level as well as some third level spells.

Additionally, you have advantage on checks made to shove an enemy Prone and any prone enemies grappled by you are considered Restrained.

While an enemy is restrained in this way, as a bonus action you can spend 2 ki points or spend your turn to detach part of your arm and leave that creature grappled, prone, and restrained for 1 minute or until they use an action to make a Strength or Dexterity saving throw to escape the restraints.

Formidable

As your markings reach full strength, your corruption seeks to spread to your enemies while your courage seeks to aid you further. Starting at 17th level, as an action you can take on each of your turns in combat, you may spend 5 ki points to force one small or larger creature that you have Grappled to make a Constitution saving throw, or, for your dominant arm, 10 ki to use a level-nine spell slot. 

On a failure for your opponent regarding your corruption, you may choose to Petrify that creature, or to Corrupt them.

Petrify. The creature is considered Restrained and must repeat the saving throw at the end of its next turn, becoming Petrified on a failure or ending the effect on a success. The petrification lasts until the creature is freed by the Greater Restoration or other magic.

Corrupt. The creature is considered Poisoned, cannot willingly break the grapple through physical means (though it could still, for example, teleport away), and takes 4d10 necrotic damage at the start of each of its turns and you regain half of that many hit points. This effect ends if the grapple is broken for any reason.