Through thick and thin you have always been there for your cherished and would do anything for them. Resulting from this mindset, you sacrificed yourself and absorbed the ever coming Abyss into yourself causing unusual changes to you body and your way of thinking. This subclass focuses on being able to only rely on yourself and no one else, seeing as they let you down in the past. They won't be able to let you down now that you don't need them.

 

Forever Hungering

For a normal human to absorb the Abyss is a difficult task, but keeping it satiated is another thing.

   After a battle you have the choice to absorb a creature into the Abyss, this is considered an action and requires concentration, however after doing this you have to make a Wisdom Saving Throw (12 save DC). If the save fails the Abyss will take over your mind for a short period and rampage, destroying anything in the vicinity, living or not. If the save succeeds you have a choice, you can either regain 10 hit points  or you can take half of the XP that you would normally get for killing the creature along with the XP that you would normally get for defeating the creature.

Unnerving Voice

 

As the Abyss takes hold more and more you start to hear an alluring voice telling you to do unspeakable things.

   Starting at 3rd level, you start hearing a voice in your head and this causes you to doubt people on whether they are being genuine or lying to you. Hearing these voices causes you to become unpredictable, adjust your alignment to the Chaotic version accordingly. Hearing this voice in your head at all times of the day gives you assurance of your reality and causes you to become resistant to Psychic Damage.

Ever Bonded

The weapon that felled the Abyss shall now fell for the Abyss.

   Starting at 7th level, the weapon that helped you defeat the Abyss is now connected to you by the Abyss. The weapon that is currently being used is now permanently attached to you by the Abyss and is able to be wielded in one hand no matter what the weapon is. The weapon that has been attached deals an extra 2d6 Necrotic damage along with the normal weapon damage. This weapon is the only weapon you are able to wield forever as your arm that is not wielding a weapon has been taken over by the Abyss deeming it unnecessary.

Unnecessary Actions

 

Keeping the Abyss contained is top priority and its not easy, because of this you have learned how to maximize your distance you can travel using the minimum energy.

   At 3rd level every 10ft you move only counts as 5ft of movement actually spent, you also gain the ability to preform a long jump without needing a run up.

Abyssal Symboisis

With the Abyss ever growing you have learned to harness that dark power and utilize it in ways beneficial to yourself.

   At 15th level, you realize the latent potential you possess and harness the Abyss incorporating it in some attacks or using it by itself. Utilizing the Abyss you can either combine them with your sword swings to make them more deadly, expel it by itself in a form of ranged attacks or allow it to coat your body in a endless armor.

Monarch of the Abyss

You don't even know if you are still in there, for all you can feel is the Abyss.

   At 18th level, you have full control over the Abyss and everything in it. You are at this point the concept of the Abyss, given a physical form and a body to harness that endless power, channel that strength and allow the Abyss to take over everything. Being controlled by the Abyss you are not able to move on your own accord and therefore do not care if you are fatigued (ignore Exhaustion and Movement limitations), also not being in control allows you to bring out your true strength that has been blocked by the limiters of your body.