Serpent vs Seth | The Winner vs Odin

 and the winner Fights Odin

Scenario : both have decided to team up to fight odin but are having second thoughts about working togather and decided not to share the throne of asgard. after one kills the other his final battle with odin  this war will be a bloodlust on battle

Odin. 
 
1.In weakned state Odin won with help of others (pretty much they were just a distraction, but it seems that Odin needs that) defeated Seth who in that fight was highly boosted. Serpent didn't show anything in Odin's level to this moment, so I doubt in him. In normal state, Seth have no chance against Odin.
2.Seth in his prime - for easy win with "current" Serpent. Normal Seth, would lose. Serpent seems to be in King Thor level.

I don’t know about Seth but Odin beat Serpent before, by killing everyone on Earth