Did floki betray Ragnar?
Hereof, why does floki betray Ragnar?
But many speculate that the slave may betray the king as requested by Queen Aslaug. Floki was tortured by his best friend King Ragnar as a punishment for killing Athelstan. Luckily, he survived the torture, and regained his strength quickly after he went to visit the Seer. And now he may have a plan of seeking revenge.
Similarly, it is asked, did Athelstan betray Ragnar?
Another shocker was that Aethelwulf and his father betrayed Ragnar and killed the Viking settlers in Wessex. Floki says the Norse gods allowed this to happen because the Vikings allied with Christians. It was Ragnar's choice but still Floki blames Athelstan and it drives him to kill.
Floki is one amongst many Vikings who could have killed Athelstan. Of course deep down Ragnar knows he is going to get revenge once he knows who did kill Athelstan, but he doesn't talk about it straight up because he has more emotional things to think about.