Demons Have Personality by John Hagee

And when He stepped out on the land, there met Him a certain man from the city who had demons for a long time. And he wore no clothes, nor did he live in a house but in the tombs.  When he saw Jesus, he cried out, fell down before Him, and with a loud voice said, "What have I to do with You, Jesus, Son of the Most High God? I beg You, do not torment me!"
Demons Have Personality

The Scriptural truth is very clear concerning demons and their personality as is evidenced by the following facts:
1. Personal pronouns.  The pronouns I, me and you are applied to demons by Jesus Christ and by the demons themselves in Luke 8:27-30.

2. Demons have names.  Jesus asked the demon spirits inside the body of them demoniac of Gadera, “What is your name?”  The demons seized the vocal cords of their host and replied, “Legion,” because many demons had gone into him. Luke 8:30-31

3. Demons have will.  Matthew 12:44 Jesus describes the will of a demon who said, “I will return to my house body of a person from whence I came out…”

4. Demons have emotions.  James 2:19 records, “Thou believest that there is one God; thou doest well:  the demons also believe and tremble.”  Trembling demons equal emotions.

5. Demons have supernatural knowledge.  When Jesus entered the synagogue to teach, the demons within a demonized man cried out saying, “Let us alone, what have we to do with thee, thou Jesus of Nazareth?  Art thou come to destroy us?  I know who thou art, the Holy One of God.”  Mark 1:23-24  The religious Jews surrounding Jesus did not know that He was the Holy One of God but the demons knew.

6. Demons have the ability to speak.  They take over the vocal cords of their host as is demonstrated in Scripture.  In Mark 1:23-24, the Bible says, “And there was in their synagogue a man with an unclean spirit; and he cried out, saying, ‘Let us alone; what have we to do with thee, thou Jesus of Nazareth?’”

Source:  Facts About Satanism in America