Probably to Paul himself. Compare Act 19:22; Act 20:4. Scarcely in the official sense of deacon.
Fellow-servant (σύνδουλος)
Used by Paul only here and Col 1:7, of Epaphras. By this term he designates Tychicus as, in common with himself, a servant of Jesus Christ. Probably not with a strict, but with a quasi official reference.