When "autem" expresses this, it means "and, then, indeed" The example from OLD: "quid tu autem? Etiam huic credis?" Pl. Capt.556 How can we translate it in a modern way?I'm asking because the translation in Portuguese is really weird. I never heard of it my entire life. I just wanted a better explanation from a native of English.
The conjunction "autem" expressing indignation or surprise in questions and exclamations
I would translate autem here as "too" or "even". Aristophontes here is shocked that Hegio seems to be believing Tyndarus's lies: "what, even you? You believe this too?" Or perhaps: "What, you too? You also believe this?"
Fundamentally it's an intensifier, which doesn't add much to the meaning but emphasizes the already-prominent tu. Aristophontes was already shocked to hear what Tyndarus is saying about him; he's then even more shocked that Hegio seems to be going along with it.