Soul Remnant

Your patron is the Remnant soul from a dying entity, whose means of survival is that of finding a willing host to contain its spirit and in exchange for this it will share its knowledge and power.

While accepting this soul into your body, a symbiotic connection is established between you and it, allowing you to learn from its past experiences and gain power. 

The remnant souls can be of either type:
Celestial, Fiend, Fey, Cursed Soul (Vampire, Lich, Wereworlf etc)

Gaze of Two Minds

As your Patron becomes apart of you and a separate living entity within you, it is able to provide resistance towards Charm effects, providing you with advantage on saving throws.

You also gain the knowledge from your patrons past lives, providing you with an additional language of your choosing based on the soul sharing your body.

Celestial Entity
Celestial

Fiend
Abyssal or Infernal

Fey Entity
Sylvan or Kraul

Cursed Soul
Dwarvish, Elvish, Halfing, Gnomish, Draconic, Vedalkin or Loxodon.

Soul Spells

You learn additional spells when you reach certain levels in this class, which you are able to cast one of these spells once a day (Per long rest) which will not expend a spell slot.
Whenever you gain a Warlock level, you are able to replace one spell you gained from this feature with another spell of the same level.

Spell List:
1st
3rd
5th
7th
9th

Each soul has access to spells from different Class Spell Lists, below contains the required information to determine which spell lists are available:

Celestial
Spell List Options: Cleric & Paladin

Fiend
Spell List Options: Sorcerer & Warlock

Fey
Spell List Options: Bard & Druid

Cursed Soul
Spell List Options: Warlock & Wizard

Soul Proficiency

At level 1, you gain a proficiency with one of the following skills which was previously known to the soul that inhabits your body. 
Choose one of the following proficiency's and add it to your character sheet.

Animal Handling
Arcana
History
Insight
Medicine
Nature
Religion

Soul Development

At level 6 you gain the following.
You have the ability to switch the base damage type of your spell to the damage type aligned with the shared soul.

Damage alignment table:
Celestial
Radiant

Fiend
Fire

Fey
Psychic

Cursed Soul
Necrotic

You will also gain the following passive abilities based on which soul inhabits your body:
Celestial
The soul provides the host with the ability to passively determine the emotional state of any living creature within 30ft radius that you can see, while being able to determine a creatures emotional state you are able to utilize this into determine the truthful nature of a creatures words providing you with advantage to Insight Ability Checks.

Fiend
The sly nature of the fiend soul that inhabits your body, enabling you to weave lies in with truths making it harder for creatures to determine if you are being honest or deceitful, this provides you with advantage on Deception Ability Checks.

Fey
The soul provides the host with the ability to visually see a Creatures alignment of any living creature within 30ft radius that you can see, this is indicated by a slight glow around its aura.
Green = Good
Yellow = Neutral 
Red = Evil
With the Fey's present combined to your own, creatures and animal can feel more at ease providing you with advantage on Animal Handling Ability Checks.

Cursed Soul
You are able to strengthen your presence, that enables you to enhance your aura and surroundings while also bringing a chill in the air that will cause a sense of dread within a creature you are communicating with and this provides you with advantage on Intimidation Ability Checks.

Soul Adapt

At Level 10 you gain the following ability associated with your shared soul.

While your you inhabit two souls within your body, the additional soul provides advantage Death Saving throws.

Also depending on which soul also inhabits your body, you get the following benefit and ability:

Celestial
As a Bonus Action, you are able to use detect thoughts equal to a number of times of your proficiency modifier per long rest.

You also gain resistance to the following damage: Radiant

Fiend
Once per short rest as a Bonus action, your body starts to irradiate heat and produce small sparks of fire which surround you presence which when hit with a melee attack these sparks will ignite into a burst of flame causing damage to the attacker 2d8 Fire damage, this effect remains active for 1 minute.

You also gain resistance to the following damage: Fire

Fey
As a Bonus Action, you are able to dispel a charm effect or remove poison condition from target you can see which can hear your voice, this can be use to a number of times equal to your proficiency modifier per long rest.

You also gain resistance to the following damage: Psychic

Cursed Soul
Once per short rest as a Bonus Action, you are able produce an intense aura that extends 30ft radius form your location, which promotes fear in any creatures within range, they must make a wisdom saving throw.

If they fail, the creature must move away from you and are under the Frightened condition till they succeed on a Wisdom saving throw.

You also gain resistance to the following damage: Necrotic

Oversoul

When you reach level 14, your connection with your partnered soul becomes fully connected and you are able to channel their own unique special abilities, these abilities can only be used once per long rest:

Celestial
When activating this ability you become a glowing beacon of radiant light, which expands for 30ft radius that is centered on you, all party members with its vicinity feels your presence and gains the effect of bless.

Also any downed party members awaken with 1 hit point and you're able to distribute a maximum of 50 hit points across party members in the aura.

Fiend
When activating this ability, your body become engulfed in arcane flames, these do not burn or cause you any damage but any enemy creatures within 30ft are instantly hit with a 5th level hellish rebuke (6d10 Fire Damage) or you can focus the flames to attack a single creature which increases damage to (12d10 Fire Damage).  Creatures hit must make a Dexterity Save, if successful the creature takes half damage, otherwise they take the full damage from this ability.

Fey
When activating this ability your body emits a vibrate array of colours, a calm and relaxing audio sound effect which is accompanied by an alluring scent which reaching out for 30ft radius that is centered on you, Selected Creatures within this aura must make a Wisdom saving throw or be subject to the spell Suggestion.

Any creature which is unable to take in 2 (Visual, Sound or Smell) of the affects from the aura has advantage on its save.

Cursed Soul
When this ability is activated its duration lasts for 1 minute, a dark aura embraces the area of 30ft radius which is centered on you, this aura embraces party members with an illusionary cloak providing the benefits of blur.

While this is in affect your own body takes on the benefits of your partnered souls previous form, gaining all the benefits but none of its previous weakness's.

Damage Resistances: Bludgeoning, Piercing, and Slashing from Non-magical Attacks