This is a video demonstrating how prayers works in all directions.  As we command spirits to come out of a person, they also come out of another person, who heard the same command.  This happens all the time when we do deliverance prayers and we do encourage people to come in just to listen in to the deliverance prayers because of this “ricochet” effect:

We do not wrestle against flesh and blood:

Ephesians 6:12 King James Version (KJV)

12 For we wrestle not against flesh and blood, but against principalities, against powers, against the rulers of the darkness of this world, against spiritual wickedness in high places.

 

We do have all authority over the power of the enemy:

Luke 10:19 Young’s Literal Translation (YLT)

19 lo, I give to you the authority to tread upon serpents and scorpions, and on all the power of the enemy, and nothing by any means shall hurt you;

 

Though we issue the commands, it is God who fights our battles.  He has done that in the past and will continue to do so in the future:

Joshua 23:10 King James Version (KJV)

10 One man of you shall chase a thousand: for the Lord your God, he it is that fighteth for you, as he hath promised you.

Deuteronomy 20:3-4 King James Version (KJV)

And shall say unto them, Hear, O Israel, ye approach this day unto battle against your enemies: let not your hearts faint, fear not, and do not tremble, neither be ye terrified because of them;

For the Lord your God is he that goeth with you, to fight for you against your enemies, to save you.

 

Essentially, we pray for people and then God delivers everybody in the vicinity with his angels and the power of his Holy Spirit.  If a person is repentant, the spirits are expelled in Jesus name.