Soul Kin

Through magics more powerful than you can even imagine, maybe even against your will, your soul has been entwined with another.  Perhaps it is a creature, something simple in purpose and design, or maybe a lover whom you have made a pact of support and safety, or maybe it is a being of power who wishes to keep you alive.  Whomever it is, your soul and the life of this other have been weaved together in a way that is not easily broken.  

Whichever the case, the following is what occurs:

• Your hit points and those of your soul kin are now combined into a total pool from which each of you may draw.  When one of you takes damage, both of you take damage.  When one of you is healed, both of you are healed.  If you are bound to a creature who would not normally live as long as your character, that creature will now live an unnaturally long life.  When one dies, the other dies also.  (When either of you drops to 0 hit points, the other will also drop to unconsciousness and will eventually die if not assisted.  In the same way, if assistance is given to either of you, both will be revived.  Because of this bond, both of you gain an advantage whenever rolls are made to determine if you are exhausted or not, as long as you are both within 100 feet of each other when the roll is called for.)
• While you are not aware of each other's specific thoughts through your bond, you are aware of and may even feel the emotions of your soul kin.  This will be represented as a privative form of communication, not with words but with feelings.  The strength of this emotional bond is more intense, the closer you are in proximity, but you will feel even the slightest mental tug of the heart no matter how far you have wandered apart from each other.  When you are actually touching each other, you will feel everything the other is feeling, for better or for worse.
• You and your soul kin will quickly begin to exchange minor characteristics.  If you are bound to a beast,  you will begin to demonstrate some of the quirks that come along with that creature.  Are they a bloodthirsty predator?  Maybe a meek creature who enjoys grazing in a mountain meadow?  Or a crafty creature that has to store enough nuts before winter?  If you are bound to a person, how are they different than your character?  How do they react to things?  What quirks in their personality might your character begin to reflect?    And if you are bound to a being of power, how might that effect your character?   What changes would occur?  You won't be gaining any new abilities through this bonding, but you may find yourself seeing people, places, and things through a perspective that has shifted.