This is nice of you to say so 😊
Once again I don't think your qualified to give advice because the scripture don't say and fasting, the word fasting was added.
Let's see what else the bible says.
The bible says everyone who will belief in Jesus will recieve a gift.
But not everyone will recieve the same gift.
Then the bible says this.
Mathew
I Never Knew You
21 “Not everyone who says to me, ‘Lord, Lord,’ will enter the kingdom of heaven, but the one who does the will of my Father who is in heaven. 22 On that day many will say to me, ‘Lord, Lord, did we not prophesy in your name, and cast out demons in your name, and do many mighty works in your name?’ 23 And then will I declare to them, ‘I never knew you; depart from me, you workers of lawlessness.’
Then the bible says this
21 Jesus asked the boy’s father, “How long has he been like this?”
“From childhood,” he answered. 22 “It has often thrown him into fire or water to kill him. But if you can do anything, take pity on us and help us.”
23 “‘If you can’?” said Jesus. “Everything is possible for one who believes.”
24 Immediately the boy’s father exclaimed, “I do believe; help me overcome my unbelief!”
25 When Jesus saw that a crowd was running to the scene, he rebuked the impure spirit. “You deaf and mute spirit,” he said, “I command you, come out of him and never enter him again.”
26 The spirit shrieked, convulsed him violently and came out. The boy looked so much like a corpse that many said, “He’s dead.” 27 But Jesus took him by the hand and lifted him to his feet, and he stood up.
28 After Jesus had gone indoors, his disciples asked him privately, “Why couldn’t we drive it out?”
29 He replied, “This kind can come out only by prayer.[
See there's no fasting here.
So what prayer must be prayed do you know.
And last question
Since your father is a preacher and your qualified how come your brother is possessed as you put it ?.