A lot of information about "Vikings" were discussed during the San Diego Comic-Con this year, and not all of the details have yet been explored. One important bit of information from a previous report from Entertainment Weekly reveals that King Ecbert (Linus Roache) and Ragnar Lothbrok (Travis Fimmel) may form an uneasy alliance. 

"He's a fascinating character," explained series creator Michael Hirst. "A good foil for Ragnar. There are many things they have in common, which they recognize. They may well, ultimately, get the chance to talk about some of the things they have in common." 

One thing that they may have in common is their war against Emperor Charles (Lothaire Bluteau). During that age, England and France were at constant war and, in this case, the saying "the enemy of my enemy is my friend" may put Ecbert and Ragnar together, at least until they defeat Charles. 

Fighting Emperor Charles will also bring back a feud with a character that ties them all together — Ragnar's brother Rollo (Clive Standen), who forged an alliance with Charles and agreed to marry his daughter. 

Rollo once forged an alliance with Ecbert but betrayed him after losing to Ragnar. Rollo has betrayed Ragnar twice now. This makes Rollo a hot target for both kings and the fact that he is working alongside Emperor Charles will make him their most wanted target. 

Fighting with or against Ecbert will lead to dire consequences, however. [Spoiler alert] In Viking lore, Ecbert was eventually the man to defeat Ragnar and kill him by throwing the Viking legend into a pit filled with poisonous snakes. His sons and wife would eventually take revenge by killing Ecbert. 

It is possible that the upcoming season will start building up to this climax while also preparing Ragnar's sons, particularly Bjorn (Alexander Ludwig), to become the new main characters.

"Vikings" season 4 premieres early 2016.