Advocate
The figurative use of "advocate" — one who stands beside the accused and pleads for him — appears in UPDV in a single verse, and there the word UPDV chooses is not "advocate" but "supporter."
A Supporter with the Father
Writing to dissuade his readers from sin while at the same time refusing to leave them in despair when they fall, John names the one who answers for them above: "My little children, these things I write to you⁺ that you⁺ may not sin. And if any man sins, we have a supporter with the Father, Jesus Christ the righteous" (1 John 2:1). The verse holds two truths together. The aim of the letter is the avoidance of sin — "that you⁺ may not sin." But the provision against sin already committed is a person, not a procedure: a supporter with the Father, identified by name and by character as "Jesus Christ the righteous." His righteousness is what qualifies him to stand for the unrighteous. The figure is judicial in shape — one party speaking with the Father on behalf of others — but the relational note is unmistakable: those for whom he stands are addressed as "my little children."