They're both in the title, hence co-leads. ("As I said."
) And somebody's name has to come first.
You'd actually have a better case with My Adventures with Superman. Lois is not named in the title, but she's certainly the "My," and therefore arguably framed as the viewpoint character.

You'd actually have a better case with My Adventures with Superman. Lois is not named in the title, but she's certainly the "My," and therefore arguably framed as the viewpoint character.