If Batman joins his parents in the game, this market resolves YES, even if there are branching story paths where he lives to crusade another day, or if he gets resurrected or whatever.
There's a decent chance that it may be unclear whether or not Batman actually dies. For this reason, I will not bet in this market. I will do my best to resolve YES or NO, but if it's totally ambiguous I may resolve to N/A.
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