Warning! Spoilers ahead for Future State: Shazam! #2 by Tim Sheridan and Eduardo Pansica!
Without Billy Batson, Shazam is worthless. Many fans have understandably come to the conclusion that, when compared to Billy, the champion known as Shazam is the true hero. Meanwhile, Billy is, well, merely a boy. Billy might possess a pure soul, which is what initially compelled the wizard Mamaragan to imbue him with the powers of Shazam, but that's about it. Shazam is the wielder of the Living Lightning. What does Billy wield? Adolescence? Amazingly, recent events have proven that Billy is more important to Earth's Mightiest Mortal than many might have realized, in Future State: Shazam! #2 written by Tim Sheridan with art by Eduardo Pansica.
In DC's distant future, Shazam finds himself in a rather precarious situation that would have been much more manageable if he could have just been in two places at once, an endeavor he understandably thought was impossible. For mankind's continual survival, he needs to prevent Raven, who bound herself to the four riders of the apocalypse, from breaking out of Hell's Rock of Eternity where Shazam has imprisoned her. But keeping an ever-watchful eye on her would leave the world exposed to the atrocities that would inevitably ensue should he stay there.
Aware of his plight, the devil, the ever-advantageous and clever fella that he is, provides Shazam with a solution; he can split the champion from the boy. Billy would be the perfect guardian, as his pureness would keep Raven's door shut. This would therefore free Shazam to continue saving Earth from the myriad of threats facing the planet. But, of course, the devil doesn't do things out of the pure goodness of his heart. He wants Shazam separated from Billy so he can take advantage of the champion's "lack of vision."
And he does. The devil literally places his own visions where Shazam's own vision should have been. What these visions consist of explains why Shazam has been murdering heroes. The devil makes Shazam perceive them as monsters, which usually ends with the champion attacking them mercilessly; he has essentially transformed Shazam into his puppet. Allowing Billy to merge with Shazam would cut the strings, but that won't happen any time soon.
Shazam might be Earth's Mightiest Mortal, but that's all he is. It's ironic that Earth's champion would lack intelligent foresight or imagination, especially as the wizard Mamaragan has claimed in some renditions that he fought evil for over 3,000 years using the powers of the Gods. This leads one to assume that, as a separate entity, Shazam should have thousands of years of experience at his disposal. And anyone who has spent that much time towards anything should be a visionary in that particular field. And yet, Shazam is somehow visionless when it comes to fighting. This proves that Shazam is not meant to be a separate entity; he needs Billy.