Are you ready for it?
Here goes:
7 Τὰ κατ᾿ ἐμὲ πάντα γνωρίσει ὑμῖν
Τύχικος
ὁ ἀγαπητὸς ἀδελφὸς καὶ πιστὸς διάκονος
καὶ σύνδουλος ἐν κυρίῳ,
8 ὃν ἔπεμψα πρὸς ὑμᾶς εἰς αὐτὸ τοῦτο,
ἵνα γνῶτε τὰ περὶ ἡμῶν καὶ
παρακαλέσῃ τὰς καρδίας ὑμῶν,
9 σὺν Ὀνησίμῳ
τῷ πιστῷ καὶ ἀγαπητῷ ἀδελφῷ,
ὅς ἐστιν ἐξ ὑμῶν·
πάντα ὑμῖν γνωρίσουσιν τὰ ὧδε.
or in English:
everything about me he shall make known to you
Tychicus,
the beloved brother, faithful servant,
co-slave in the Lord,
whom i am sending to you for this reason:
that you might know about me,
and that your hearts might be encouraged.
[whom i am sending to you] with Onesimus
the faithful and beloved brother,
who is from you,
everything here shall they make known to you.
What stands out is both the florid descriptions of Tychicus and Onesimus, but also the way in 4.8 Tychicus' name doesn't get a mention for some time. This is perhaps to allow the 'making everything about me known to you' to frame the section.
This idea of what's happening with Paul and Co. also gets a jersey in the middle, but also perhaps the purpose of the letter: that your hearts might be encouraged. The whole theme of the Supremacy of Christ is an encouragement to those who are trying to be holy in a world which isn't, and trust in Christ in a world which doesn't (1.2 - nb TNIV, NIV11, Gk).