Angels Are Personal Beings
Angels are pure spirit, but that doesn't mean they are just floating apparitions. Angels are personal beings, and likewise, the evil angels did not lose their person-hood, when they became demons. Angels have the three primary attributes of person-hood, which are intellect, emotions and will.
Angels have intellect. According to I Peter 1:12, they long to understand more about our salvation. In other words, they can think, and they talk with people. And they have emotions, for we read in Job 38:7 that they were filled with joy at creation. Jesus said in Luke 15:10 that the angels rejoice over one sinner who repents and does penance.
Angels also have a will, because each angel had the choice to follow Satan in his rebellion or remain true to God. Satan exercised his will when he tried to usurp God's throne.
We see all three of theses attributes demonstrated when Jesus comforted a demon-possessed man who lived naked among the tombs. (Luke 8:26-31) the multitude of demons who were tormenting this man exercised their intellect first of all by recognizing Jesus: “I beseech thee, do not torment me.” (verse 28). So Jesus gave them permission to enter a herd of pigs nearby (verse 32).
The demons also expressed their emotions and wills by expressing fear of torment and begging Jesus not to send them away where they could no longer be active. Many bible teachers believe that the demons calling Jesus by name was not just a recognition of Him, but it was an attempt to gain control over Him. That could be why Jesus often told demons to be quiet when they spoke to Him (Mark 1:25).