philippians

The Epistle of Paul to the Philippians is written in the second person plural, except for the following verse.

Philippians 4:3 (NASB)
³ Indeed, true companion, I ask you also to help these women who have shared my struggle in the cause of the gospel, together with Clement also and the rest of my fellow workers, whose names are in the book of life.

This verse appears to be parenthetical, because here we find the Greek word, σύ, which is the second person singular; that is, in the following verse he reverts to the second person plural of address for the remainder of the epistle.

To whom then was Paul referring as the “True Companion” in this verse, if we understand that the epistle was supposed to be addressed to “all the saints in Christ Jesus who are in Philippi” in general (Phil 1:1)?

Was this perhaps some literary device to address each individual in the Philippian Church to take responsibility in helping Euodia and Syntyche to live in harmony?

In other words, was Paul aware of the “Bystander Effect“ (or Genovese Syndrome) in the First Century? The thesis avers that larger numbers of people decrease the likelihood that any one person in particular will step forward to help those in distress; responsibility to help thus remains diffused among the large number of people. That is, the individual must be addressed in order to prompt the response to assist those needing help.

In this context was the “True Companion” therefore each and every believer in Philippi (thus Paul’s attempt to mitigate the “Bystander Effect”), or was perhaps the “True Companion” actually some particular individual person in Philippi? Thoughts?