Friend, to understand what JESUS said and says, He is forever and ever, it is necessary, first of all, to have the Spirit of JESUS. It is impossible to understand what JESUS says to those who have not the Spirit of Christ..
Having the Spirit of Christ is truly necessary to understanding God's Word. In fact, that is exactly what Christ told His disciples before dying on a cross:
John 16:7-9
King James Version
7 Nevertheless I tell you the truth; It is expedient for you that I go away:
for if I go not away, the Comforter will not come unto you; but if I depart, I will send him unto you.
8 And when he is come, he will reprove the world of sin, and of righteousness, and of judgment:
9 Of sin, because they believe not on me;
"The Comforter" is the Spirit of Truth. Christ foretells His coming cannot precede His Own departure. When He comes, He will reprove unbelievers (v.9).
John 16:12-14
King James Version
12 I have yet many things to say unto you, but ye cannot bear them now.
13
Howbeit when he, the Spirit of truth, is come, he will guide you into all truth: for he shall not speak of himself; but whatsoever he shall hear, that shall he speak: and he will shew you things to come.
14 He shall glorify me: for he shall receive of mine, and shall shew it unto you.
Because we know He was sent to minister to unbelievers, we can say that His priority is revealing the Gospel of Christ to unbelievers, as these two passages teach.
But here's the cool thing:
John 14:15-23
King James Version
15 If ye love me, keep my commandments.
16 And I will pray the Father, and he shall give you another Comforter, that he may abide with you for ever;
17 Even the Spirit of truth; whom the world cannot receive, because it seeth him not, neither knoweth him: but ye know him; for he dwelleth with you, and shall be in you.
Christ is the Consolation of Israel, thus "another Comforter" will be sent. He is called here "the Spirit of Truth." He will, according to v.16—be with believers forever (contrasted to Christ not being with them much longer).
Note lastly that the Spirit of truth is already "with" the disciples but is not "in them." This is the reference to the eternal indwelling of God in the believer,
after He returns and sends the Spirit of Truth.
18 I will not leave you comfortless: I will come to you.
Did you catch that? Here it is again:
18 I will not leave you comfortless:
I will come to you.
So, "another Comforter," designated as Christ (The Son) coming. This is not hard to understand, seeing that the Father, Son, and Holy Ghost are one and the same. Three distinct personages yet One. So far, we see that the coming of the Holy Spirit is also the coming of The Son.
19 Yet a little while, and the world seeth me no more; but ye see me: because I live, ye shall live also.
20 At that day ye shall know that I am in my Father, and ye in me, and I in you.
"At that day," the Lord states, believers would know that The Son is in The Father—and the believer.
21 He that hath my commandments, and keepeth them, he it is that loveth me: and he that loveth me shall be loved of my Father, and I will love him, and will manifest myself to him.
22 Judas saith unto him, not Iscariot, Lord, how is it that thou wilt manifest thyself unto us, and not unto the world?
23 Jesus answered and said unto him, If a man love me, he will keep my words: and my Father will love him, and
we will come unto him, and make our abode with him.
So, "at that day (when The Son has returned to Heaven and the Comforter is sent, those who love Jesus will be indwelt by The Father, The Son, and The Holy Ghost ("Ghost" being the term used in Old English that represents "Spirit," so the two words mean the same thing (as opposed to a spectral figure of a human that has died).
The reason why we are indwelt by God the Father, the Son, and the Holy Ghost is because God is One. There is no brother in the Trinity. The coming of the Spirit of Truth (the Holy Spirit) is the coming of the Son, and is the coming of the Father—to live in the believer that responds to the truth the Holy Spirit reveals to them as unbelievers.
1 Peter 1:11-12
King James Version
11 Searching what, or what manner of time the Spirit of Christ which was in them did signify, when it testified beforehand the sufferings of Christ, and the glory that should follow.
12 Unto whom it was revealed, that not unto themselves, but unto us they did minister the things, which are now reported unto you by them that have preached the gospel unto you with the Holy Ghost sent down from heaven; which things the angels desire to look into.
The Holy Spirit also reveals the Gospel through ministers.
And I am afraid I only read half of the thread; did you ever present Scripture you base the Holy Spirit being the Son's brother rather than being God Himself?
God bless.