Survival. The one thing everyone understands, no matter it's intelligence or sentience. The ambition to keep breathing and don't stop, to keep the heart beating, is something ingrained in the core of every living being. Everything; including a certain chromatic living goo which you met by a chance encounter. Usually, it's host's organs wither away within hours, but not you, somehow. Your DNA seems to match with the parasite's alien genes, meaning you two are a perfect match genetically and have achieved symbiosis. This doesn't mean you're happy together; personalities, goals and ethics tend to vary between humanoids and aliens.

Regardless of the circumstances of you're meeting or you're opinions of each other, you know depend on each other for survival; The parasite needs a home, and in exchange, you can leave behind your old warclad armor. You've got something much better now, the likes of which this world has never seen

Symbiosis

Your armor is a parasite that lives inside you, waiting for your call. After you gain this feature at 3rd level a voice enters your mind. It is the thoughts of your armor, greeting you and explaining the current situation. It functions like most other sentient magic items, and much of its personality and abilities are dependent on story details and your DM's discretion.

Abilities Your armor has its own Intelligence, Wisdom, and Charisma scores. These are determined by the player, who uses the Customizing Ability Scores (Point-Buy) variant of determining ability scores from page 13 of the Player's Handbook. The player has 17 points to spend on these three ability scores, rather than 27. No bonuses apply to these attributes. It knows 2 skills from the Warclad Proficiencies, and if both you and your armor are profiencent in a skill, you may add your profiency bonus twice.

Communication The armor can communicate telepathically with you as long as it is within you, and can speak any language you know.

Senses When not worn, the armor has a blindsight with a range of 30 ft, as well as a sense of touch. When worn by you, the armor's senses and yours are one in the same, and you can gain the benefits of its blindsight. If you already have blindsight, the armor extends its range by another 30 feet. When wearing the armor, you are partly melded with it, and anything that touches the armor's surface feels as if it is touching your skin.

Alignment The armor has an alignment. It might be influenced by your own alignment, or have one chosen by the DM.

Special Purpose The armor may have an objective it pursues. How much that purpose aligns with the player's goal is up to the DM, but in order to support the longevity of this subclass, it's best that the armor and the player character share a common goal. The armor will follow any command the warclad gives it, unless the warclad has ultimately betrayed the armor's purpose.

In your interactions with your armor, it is an NPC like any other. It might offer advice, or tell you of its past and purpose (if it knows anything on the matter). However, it can't do much outside of interacting with you. It cannot make checks or saving throws while inside you. When your armor is at 0 hit points, the voice goes silent, and does not return until it has gained 1 hit point.

Surviving outside the body Should you, it's main host, ever be killed, your parasite can still survive. It exists your body in the form of a Small sized goo. It has your twice your Warclad level hit points, a speed of 35, an Ac of 12, A strength score of 10, a constitution score of 12, a dexterity score of 15, and a profiency bonus equal as yours. It can slip through gaps as narrow as 1 inch without sacrificing movement speed and can escape grapples by using 5 movement speed. It can survive outside a body for 8 hours, after which it dies and can be brought back to life the same way as any player character. It can inhabit a willing creature using it's action; unwilling creatures need to make a DC 10 constitution saving throw to avoid this.

Inhabiting foreign creatures While inhabiting a creature it can communicate telepathically even if they don't share a language. The parasite can attempt to encourage actions but ultimately has no control. Unless the creature inhabited has at least 3 levels of Warclad and has chosen the Fleshbinder or the Parasite Combat Chassis, their organs will begin to wither after 2d20 hours. After the time has elasped, the creature suffers from disadvantage on all checks and rolls to do with strength, constitution or dexterity while the parasite inhabits them. 3d12 hours after a creatures organs begin to wither it must make a constitution DC 10 saving throw or die, after which the parasite is forced out again. The creature will take 1d12 hours to recover and un-wither their organs if they parasite leaves their body. The parasite is only loyal to survival, and it's main goal is to reunite with it's original player character. Unless it knows the creature well, such as the creature being the party member of the parasite original host, the parasite will not spare them and use them until they die.