Ok, so you have a Character who has had his squad turned to a pulpy mush on the battlefield, and he is the only one left, and he run into an enemy unit in the same situation. If he and the enemy unit come to CC, is that automatically a challenge?
I am wondering because Aun'shi has some rules that only apply when in challenge. So if he were going 1 on 1 with a Commissar or SM captain, would it count as a challenge automatically? Or would one of us still have to declare it, because when you are on your own, I don't believe you can refuse a challenge can you?
I think you can always refuse a challenge... it'd just be really freaking stupid in a 1v1 combat. But yes, I believe that you do have to declare it.
The Heroic Stand rule from the rule book.
"A unit that consists only of a single character cannot refuse a challenge. He's got nowhere to hide."
It is not a challenge; a challenge only takes place if one is issued, and if one is issued then it has to be accepted as neither model can refuse (see Heroic Stand), but unless one player actually issues a challenge, no challenge takes place - it's just a combat between two one-model units!