This post covers the entire Call of Duty run, which was comprised of several miniseries. First, The Brotherhood focused on firemen. It was a semirealistic portrayal of the heroic work of firemen (conceived in the wake of September 11), but added a supernatural aspect around a ghostly girl who appears at the scene of a particularly dangerous fire.
She weaves through all series. The next one follows the same story, but focuses on police officers.
Peter Parker appeared–without his Spidey duds.
And finally, we get to EMTs with The Wagon, and we are finally tied directly into the 616 universe when Nick Fury and Dum Dum Dugan show up to help figure out what’s up with the girl (and also an evil dude who is torturing what appears to be a new mutant who emerged during The Precinct).
After this miniseries, Marvel greenlit an ongoing feature all three first responder teams.
But fans didn’t go for it and it was cancelled after four issues.
No, of course none of this turns into anything in the larger 616 storyscape. But it was an interesting experiment.