As believers in Jesus, we are filled with the Holy Spirit. That happened the day we accepted Jesus as our Savior. He is a permanent fixture in our life and will never depart from us. He was a gift to us from Jesus, someone to accompany us and give us comfort. Jesus knew we needed him because of the trials that we face on a daily basis. He helps us by convicting us of sin, illuminating the truths of the scriptures, and draws us close to Jesus. So much of the scripture points to Jesus and the Father, and that's the job of the Holy Spirit, to shine the light on their holiness; I think sometimes we forget how important He is because of that. Jesus spoke about Him and His name depicts who He is and shows His deity. He is the one who gave the writers the inspiration for the scriptures. He is very humble and doesn't toot His own horn, because of this, we may not notice Him, but don't be naive, His seal is on every word of the scriptures.
When the Spirit of truth comes, he will guide you into all the truth, for he will not speak on his own authority, but whatever he hears he will speak, and he will declare to you the things that are to come. He will glorify me, for he will take what is mine and declare it to you. John 16:13-14