One of the unfortunate things about being in a small community (and not, for example, in a motherhouse) is that on our special feast days, we rarely have the experience of the Mass of the feast. We try to do what we can to solemnize the day, but for the Mass, we get the usual daily liturgy (unless a priest friend is available on the feast day). In the Pauline Family (as well as for the Palottines), today is the Feast of Mary, Queen of the Apostles. The Mass for this feast includes the Pentecost narrative from Acts and the Crucifixion from the Gospel of John ("Behold your mother"). The readings for Saturday of the 7th Week of Easter, on the other hand, are both endings: the conclusion of the book of Acts and that of the Gospel of John. In a way, I suppose that's only fitting: the Easter season is at its end, too, with tomorrow's Feast of Pentecost.
Clearly, though, Pentecost is not something of a "finishing touch" on the work of Christ; the Gospel doesn't "end" in the Upper Room! Something like that is hinted in the Gospel itself, with the question of "the Beloved disciple."
Jesus has just told Peter that "when you are older, someone else will tie you up and take you where you would not want to go" (and in case we missed the point, the Gospel writer makes it very clear: "this he said indicating by what death Peter would glorify God"). Jesus, crucified and risen, tells Peter, "Follow me." And what does Peter do? He looks around and sees "the Beloved disciple."
"What about him?"
"What if I want him to remain until I return?" Jesus asked, rather ambiguously.
The wonderful thing about this Gospel is that the Beloved disciple is never named: he is me, you, any and every single disciple of Jesus! And Jesus does want "the Beloved disciple" to remain until he comes again!
The coming of the Holy Spirit is meant to ensure that.