Yes. In cases of possession or attempted possession this is known as courtship. While a demonologist or exorcist can analyze how the stages of possession occur or what actions/lack of actions by the subject ultimately led to the breakdown and possession, why a demon selects a particular victim is harder to figure out and occasionally just a flat out mystery. There tends to be a particular vulnerability in the core of the subject's personality that attracts a demon. Often it is a confusion in the fundamental concepts of selfhood. In known cases the demon tweaked that area in the subject by suggestion and then assesses opportunity by the response. The "tweaking" tends to be exceptionally subtle, and doesn't accelerate until a secure foothold in the connection is established. This process can go on for years, even decades. So yes, the same demon can lurk around a subject for years, and gaps in the presence of the demon are common.

There are different types of demonic manifestations depending upon the agenda. If possession is the goal the manifestations tend to be personal, subtle, suggestive, comforting, inspirational and aimed towards an insight or "enlightenment" that is fundamentally different than core human development. Once accepted by the subject - and here I don't mean possession but acceptance of the presence or interaction - the presence gradually becomes more influential and eventually domineering. The common area courted or attacked is in the realm of ideas, and confusion of the ideas.

A poltergeist type manifestation tends to be outright strange, scary or dynamic. These are bolder manifestation that center around either a place or an individual and tend to involve blatant paranormal activities. They generate fear, fascination and excitement - all energies that are simly fuel for the demon.

Ultimately, possession and other manifestations entail some form of consent by the host. But consent is also a subtle thing. Consent can come in the form of acquiescence, interest, admiration, intrigue, compassion or fear.