I agree, that's why I put animosity in quotations. You would expect there to be beef (heh) between Asterion and Nikos; especially if you didn't trick Argos twice. A combat competition is a good chance to subvert those types of expectations. There might be some but after their chat and if they carried on an online relationship, I could see Asterion being understanding of the situation (especially if Nikos tells him everything about the intent of the Argos role) and be forgiving. Though I could also imagine Asterion being playfully rough and intimidating with him, all in good fun.