Καὶ μεθ᾽ ἡμέρας ὀκτὼ πάλιν ἦσαν ἔσω οἱ μαθηταὶ αὐτοῦ καὶ Θωμᾶς μετ᾽ αὐτῶν. ἔρχεται ὁ Ἰησοῦς τῶν θυρῶν κεκλεισμένων καὶ ἔστη εἰς τὸ μέσον καὶ εἶπεν· εἰρήνη ὑμῖν.Eight days later, his disciples were inside again, and Thomas was with them. Although the doors were locked, Jesus came and stood among them and said, "Peace be with you." [ESV]
I was surprised to discovered that the "was" in the clause "Thomas was with them" isn't present in the Greek; it's just "Θωμᾶς μετ᾽ αὐτῶν." I had a couple thoughts about this, although I'll admit they may be a bit far-fetched.
Most of the translations I lookt at render it like the ESV above and supply an implied verb:
Thomas war bei ihnenThomas se trouvait avec euxThomas was with them [NIV]
The Latin Vulgate and the NKJV are the exceptions:
Thomas cum eisThomas with them
I think it's possible to see Thomas as part of the plural subject of the verb "were." Put an-other way, it would be "his disciples and Thomas with them were inside...." Granted, the "with them" is a bit redundant then, but if Thomas is included with the other disciples as the subject of the sentence, it provides something of a foreshadowing of his return to faith after seeing Jesus' wounds. In grammatical structure and in faith, he's part of the group again.
Alternatively, the lack of an explicit verb for Thomas' being there mirrors his lack of faith.