In the Versus version, Prompto was a traitor working for Niflheim. However, as he stood there watching the destruction and smoke rising from the palace with a bowed head, I felt that he had no intention of harming Noctis, nor did he want to stab his friend in the back; he was simply forced to do so under Niflheim's threats and pressure.
Prompto in the Versus version might actually be kind-hearted as well
@_bazztek I mean, if the plot of the story was different from the beginning, but there is no problem with this path of the story, as I prefer it a lot."
@_bazztek I know about the information regarding him being Noctis's friend, but I thought the rest of the speculations were actually the main idea of the story. However, I think the idea of Prompto being a traitor is quite interesting :)