After being unconscious for longer than 3 hours they must make a CON saving throw of 13+ or become possessed. On a successful save they don't become possessed. On a failed throw, roll a D4, If it comes up between 1-2, They are possessed by a demon. 3-4, possessed by an angel.

For 2 hours the human is possessed by a demon. This causes their alignment to become lawful evil, gain 5 STR, increase damage of melee attacks by 25%, lover INT by 3, and  lower WIS by 3. If they fall below 30% of their health they drop out of this form, this also causes "Rise from evil" to activate.

The human becomes possessed by an angel. This causes their alignment to become Lawful good, lose 3 STR, gain 3 INT, gain 3 WIS, gain 2 CON, have access to all first level cleric spells, and max HP to be lowered 10%. if they fall below 30% of max health they leave angelic possession, this also causes "Fall form grace" to activate

For twice as long as "angelic possession" lasted these effects remain, your movement speeds are halved, you become unable to attack, and if you activate a spell roll a d20 if the roll was less than 5 the spell's target changes to you.

For twice as long as "demonic possession" lasted gain these effects: your movement speed is halved, any humanoid creature you can see that you don't see as friendly you must attack them.