One would expect to read here the singular form, servant.
Then the reference would obviously be to John as the next link in the chain (Revelation 1:1). The plural, though, requires our thoughts to go to the final link in the chain of revelation, that is, the seven churches of Asia Minor (Revelation 1:10) and indeed all those who hear and who keep
(Revelation 1:3) this revelation over the span of centuries. That these recipients are termed servants
(= slaves) is not a slur on these addressees but speaks to their privileged position as property of Jesus Christ (purchased by his blood, Revelation 1:4: firstborn of the dead
; Revelation 1:5: freed us from our sins by his blood
; Revelation 5:6: Lamb standing, as though it had been slain
) and so heirs to all Christ’s glory. Indeed, so prized are these servants
that the Lord God is pleased to share with them his plans for the New Testament dispensation!
6 And he said to me, “These words are trustworthy and true. And the Lord, the God of the spirits of the prophets, has sent his angel to show his servants what must soon take place.”