Laurel and Hardy. Batman and Robin. Superman.
Which of these doesn’t quite fit?
Yup, it’s the guy who can’t handle Kryptonite. If Superman is in trouble, there’s almost no one to rescue him. But Hardy or Batman can get into all kinds of crazy trouble, and they’ll always have a nice partner there, ready to back them up.
The same applies to what I call the “Double-Whammy Headline.” It’s just like the usual compelling headline that draws in your reader … but it’s got backup.