The Moon, The Sky, Forever

30/06 USAGI’S BIRTHDAY

 Ardyn is a tricky, theatrical creature and was already messing with Noctis’s head way before the end of Chapter 11. I believe that he makes himself look like Prompto and vice versa as early as the  "time stitch".

Shortly after the time freeze,  Noctis turns around and suddenly sees Ardyn standing there. But it was actually Prompto innocently talking about the weather when his best friend loses his goddamn mind and tries to murder him. 

This entire train sequence was Noctis attacking Prompto, not Ardyn. Take note of the weird, off kilter dialogue during the chase and ‘Ardyn’s’ different voice dictation. Poor Prompto was begging for Noctis’s mercy the entire time. And no matter how violent Noctis got, his loyal friend never retaliated. 

Fake Prompto then wakes Noctis up and they both fight the Niflheim along side each other. This leads to the top of the train where he sees Ardyn holding Prompto up when it’s really the other way around. And thus Noctis is tricked into shoving his poor best friend off the train.