It is always easier to talk with a person you know - same with the Holy Spirit, who is a Person.
And who is “He”? Maybe what is He is better, at first…
Aquinas pictures Him as the Will of God actualizing the union with what the Will of God loves. He is God uniting Himself with the Beloved, and pictured in the image of God’s Breath going out and into the Beloved, so the Beloved breathes in the Lover Himself. One proper name given for the Holy Spirit is “Love” (actualized, or “satisfied”) So the Father and Son have a Satisfied Love with us in that they themselves, in their “Breath”, are in us, united to us (which is what a Lover Wills, union with the beloved).
With the Holy Spirit within you, received and in fullness from your Baptism and Confirmation, you have literal union to the Father and Son within you, animating your own soul with Faith, Hope, Charity, so that you also can will union with God, and willfully satisfy union with Father and Son. We do our works of will through our bodies, meaning our actions, words, thoughts. So for us to actualize our Love, our desire to be one with God, we may pray, we may help someone in need, we may go to Mass to participate with Him in the Sacrament, we may sing, we may tell others of Him.
So there can me many ways of addressing the Person who is the “Father united to you” (4 words are the Holy Spirit, not the word Father by itself), not the “Father in Heaven”, but the Father who is in with YOU, and to address “Jesus united to you”.
You have “Union” with the Father and the Son when you have the Spirit. Love requires Union, being One. When Love is “satisfied” there is Oneness. When you say, “Father” and understand he is right in front of you saying, “Yes, I am here with you”, then you are praying “In the Spirit”, in Union with Him, which is the Holy Spirit. Same with Jesus. This is different that trying to visualize him being in front of you, it is knowing he is with you so you don’t have to try and visualize anything.
I’ve been rambling a bit, trying to organize my words, but I guess it is too late tonight for that. Hope this all fits your question.