This study explores the language of the Histories of Agathias Scholasticus, the sixth-century poet and historian. Through two case studies – the syntagm πλὴν ἀλλά and the optative future – and their synchronic and diachronic contexts, it argues that Agathias’ classicizing prose should not be seen as a flawed version of Classical Greek. Rather, his usage reveals a stylistic negotiation between inherited literary models and contemporary linguistic developments. Agathias’ case demonstrates how the choices of individual authors – often hidden behind modern labels like ‘linguistic classicism’ or ‘highbrow literature’ – illustrate the evolution of high-register Byzantine Greek and challenge previous assumptions about its rigidity.