ὅτι Πέρσαι οἵ τε θεασόμενοι ὑμᾶς ἔσονται καὶ οἱ ἑψόμενοι ὑμῖν καὶ οὐκ ἐάσοντες
why does he add the articles here to predicates? or is it demonstrative: some of the Persions will be watching you and others will follow you?
I think the articles are “substantivizers” (CGCG 28.23-25) - “Persians will be the ones both watching and following you”, i.e. “Persians will not only be your witnesses but will also follow you…” in Miller’s translation. For a some… others… meaning I’d expect maybe a men… de… construction.
I think it’s easier with Persians predicate: “…will be Persians”. And then the articles are just the normal ones that come with the subject of the copula. Both the X and the Y will be…
I think you are right, grammatically speaking, but it sounds somehow weird to me.
I looked up the context to see if you were right, but I still think that Persians are predicate: σὺ δὲ τοῦτο μέμνησο … ὅτι Πέρσαι οἵ τε θεασόμενοι ὑμᾶς ἔσονται καὶ οἱ ἑψόμενοι ὑμῖν καὶ οὐκ ἐάσοντες ἐρήμους ὑμᾶς ἀγωνίζεσθαι. [I had wondered what that ἐάσοντες was all about.]
The internal logic of Persians predicate: The ones who will have your back are Persians, and therefore won’t leave you in the lurch.
Ignoring the articles and going with the other predicate would not be logically self-contradictory, but there’s no rhetorical coherence: The Persians have got your back and also won’t leave you in the lurch. That just seems like a jumble of statements to me.
Maybe Xen. wants here to put stress on the loyalty of the Persians: remember that those who will watch you and follow you will be Persians and will not (due to their loyalty) let you alone.