(Luke 6:18 NKJV) as well as those who were tormented with unclean spirits. And they were healed.
(Acts 5:16 NKJV) Also a multitude gathered from the surrounding cities to Jerusalem, bringing sick people and those who were tormented by unclean spirits, and they were all healed.
They are indwell the wicked and are involved in deceiving the nations:
Fallen angels on the other hand seem to inhabit places and realms.
(2 Peter 2:4 NKJV) For if God did not spare the angels who sinned, but cast them down to hell and delivered them into chains of darkness, to be reserved for judgment;
(Jude 1:6 NKJV) And the angels who did not keep their proper domain, but left their own abode, He has reserved in everlasting chains under darkness for the judgment of the great day;
There is no Scriptural record of anyone being possessed or inhabited by a fallen angel although Satan temporarily “entered into” Judas and will finally incarnate as the Anti-Christ. (Rev 13). Satan and other fallen angels (such as the prince of Persia) are generally portrayed as animals such as goats or dragons or spirit-beings operating outside human bodies.
One possible explanation is that Satan controls the “kingdoms of the world” ( 1 John 5:18,19) which are then individually assigned to fallen angels or principalities and powers, (Daniel 10) who then control the less powerful individual demons and unclean spirits and other spirit beings in that territory. Thus demons moving out of their territory into the area of another “spiritual warlord” are terrified. (see Mark 5:10). Some theologians describe demons as fallen angels. That is probably not strictly correct. It would possible be better to say that spirit beings, demons, unclean spirits, territorial spirits and fallen angels are all different parts of Satan’s fallen kingdom.