Possession (ability)

Not to be confused with possession meaning a personal belonging.

The act of possession (AKA overshadowing) is a specific power that demons and angels are capable of performing on mortal creatures such as humans and animals.

Canon Media
Although not directly present within the original Welcome to Hell comic or film, this ability is present in Wester's notes for possible future works. As she states, Sock is capable of possessing Jonathan under certain circumstances; likewise since Mephistopheles is a deity figure, it is more than likely he too has this power.

UC Stories
Within the Universal Clarification Series, possession is a capability by demons and angels alike, whether they are novice or expert-level figures. For however long a human host is possessed, they retain full awareness of their overshadower's actions and are reduced to a "mentally imprisoned" state until either the possessor leaves willingly or the host repels them through sheer willpower.

Story Usage
Sock first learns that he can possess people after successfully overshadowing Jonathan, which allowed him to use his body to "have a field day," to put it simply. However, he could only maintain control over him so long as Jonathan's willpower did not exceed his own; once it did, he was expelled from his body and Jonathan regained his free will after a short "dizzy spell." Such an event occurs in "First Possession." More to come later!