Jesus is the Vine

“I am the true vine, and my Father is the husbandman.”
— John 15:1

The main vine teaching runs through John 15:1–8. Jesus compares Himself to the vine, the Father to the husbandman/vinedresser, and His followers to branches. The main idea is: a branch cannot bear fruit unless it stays connected to the vine; likewise, believers cannot bear spiritual fruit unless they abide in Christ.

The part you’re calling a “deviation” is probably John 15:9–10, where Jesus briefly shifts from the vine/branches image into love and commandments:

“As the Father hath loved me, so have I loved you: continue ye in my love.”
“If ye keep my commandments, ye shall abide in my love…”
— John 15:9–10

Then in John 15:11–16, He continues explaining what that “fruit” looks like: joy, love, obedience, friendship with Christ, and being chosen to “go and bring forth fruit.” So it is not really leaving the story completely — it is Jesus explaining the meaning behind the vine image.

So the passage is:

John 15:1–8 — vine and branches
John 15:9–10 — love and obedience
John 15:11–16 — joy, love, friendship, and bearing fruit