Phenex

Relationship with Shelley
Phenex was summoned via an Ouija board by the cousin of S.W. Shelley. He slaughtered everyone above the basement level of the house. Upon realizing that Shelley was a suitable vessel to keep him anchored to our plain, he immediately made them an offer which they gladly accepted. They have been cohabitating Shelley's body for the last 14 years and over that time their relationship has grown from awkward roommates to caring deeply for each other and being each other's most trusted ally.

Season 1
Phenex is with Shelley for the entirety of season 1

Season 2
Phenex is with Shelley for most of season 2. He briefly left to inhabit the body of Crystal Moore for the sake of his own safety but returned to Shelley after a few weeks. At the end of season 2 Phenex is shot by George while trying to reason with him. He seemingly dies not long after in the arms of Shelley and tells them that they are the only human he has ever believed in. However statements made by the Goddess Hek, imply that he may actually be alive somewhere.

Season 3
Has been banished somewhere and needs to be summoned by Shelley again. Can still to some degree communicate with Shelley but thus far it has only been to tell them to go to London.

Shelley finds Phenex’s Medallion, which can be used to re-summon him.

Shelley finds Phenex again after accidentally freeing Shax from Hel.

After Sarah dies Phenex also loses all of his memories and his current status and location is unknown.

Relationship with ‘Shelley’
So Shelley’s cousin didn’t actually summon Phenex. Phenex and ‘Shelley’ first met centuries earlier when one of ‘Shelley’s past lives summoned him correctly and intentionally, with the goal of selling their soul to him in return for powers. Upon this incarnation’s death Phenex realized that he actually liked existing in our world and the person he had been running around with. So rather than taking ‘Shelley’s should back with him, he allowed them to reincarnate, chilled for a while, and waited for a good moment to reintroduce himself. This is basically what happened on the night of the sleepover. Shelley is just the next incarnation in a long line and the presence of the ouija board was a good enough excuse from his perspective. He has always hid this all from every incarnation.

Phenex somehow chose Shelley to be given power before they actually summoned him for the first time. He gifted them a spell book that they shared with their friend Alexandra

Something happened in London in 1666, likely involving Alexandra

Phenex was banished once before and that incarnation managed to re-summon him.

Fun Facts
Phenex’s pronouns are He/They.