Jesus had authority over demons.
Wherever Jesus went, crowds gathered. Demoniacs were often healed in those crowds.
In some cases, the demons became disruptive (see Mark 3:10-11 and Luke 4:41; see also Acts 8:7, where demons shrieked in Philip’s large meetings as they were driven out of people).
Most of the time, Jesus commanded the unclean spirits not to reveal His identity:
“In the evening, when the sun had set, they brought to Him all who were sick and those who were possessed with demons. The whole city was gathered at the door, and He healed many who were sick with various diseases and cast out many demons. And He did not let the demons speak, because they knew Him” (Mark 1:32-34).
Regardless of the behavior of the demons, Jesus drove them out with as little as a single word (see Matt. 8:16). He also healed people who were “troubled by impure spirits” (Luke 6:18, NIV). This seems to imply a lesser degree of demonic influence—”affliction” or “oppression” as opposed to “control” or “possession.”