The Batman/Rorschach crossover seems obvious. They have a fight scene with a stalemate, and firmly shake hands and respect each other's ways, agreeing to disagree, at the end of the story. There is a sequel, and a lunchbox.
The lunchbox is necessary to catch my vomit.
If I hear any of these stories are ok, I might have a look. We'll see.
Which reminds me: what was the name of that title Pro you were recommending to me last year?