He'll probably never admit it, not even to the rest of the DC Trinity, but Batman feels like there's a hero who's inspired, and it's someone he mentors.
When picking new members for the Justice League, Batman casts an unexpected teenage hero who inspired him: Shazam. Throughout his history in the DC Universe, Batman has taken countless teenage heroes under his wing. Obvious names that come to mind include the many kids who became Robin under his watch, other sidekicks like Batgirl, and even those destined to succeed him under Batman Beyond's Terry McGinnis. However, he brings more teenage heroes into The Apprentice than he does in the Bat-Family. Shazam is one such oft-forgotten teenage hero.
The former Captain Marvel is a unique case in that although his body assumed the appearance of a fully grown adult in combat, his secret identity was that of a child named Billy Batson. Adopting the powers of the eponymous wizard Shazam, all Billy has to do before reaching the battlefield is shout "Shazam!" In a thunderclap, he is dressed as the eponymous Shazam. Working alongside Batman as part of the Justice League makes him more of a colleague of Batman than an intern, but since Shazam still has ideas As a kid, a team veteran like Batman took on the responsibility of showing him the ropes when the time was right. An example is from Shazam Vol. 3 #12 by Jeff Loveness and Brandon Peterson, in which Batman gives young Billy advice to use his youth to figure out who he wants to be, not the hero he's trying to emulate.
Batman expressed desire to continue mentoring the boy in Justice League of America #1, directed by Brad Meltzer and Ed Benes. When naming possible new additions to the team, Batman's first choice was Shazam (then known as Captain Marvel), reasoning that they could help him reach his full potential. However, in an internal monologue, Superman implies that he knows that Batman secretly wants Shazam for another reason: simply because he's really "good." Batman would never admit it, but he thinks Shazam is a good fighter as well as a good guy. "In The Dark Knight, a little light makes you feel better."
Shazam Is The Symbol Batman Wants To Be
Which makes perfect sense, considering how Batman strives to be Gotham City's symbol of goodness, justice, and most importantly, hope. This proved to be difficult, and often, When Batman similarly strives to be a prominent symbol of fear. Sure, he's efficient, but it's hard to inspire hope in the hearts of Gothamites when the mere mention of his name triggers fear.
At the same time, Shazam is exactly the symbol of hope that Batman wants to be, except that Shazam is a symbol of such a world, not just a city, and without any brooding. Shazam can actually inspire people, including heroes like Batman, as a symbol of light, which is why The Dark Knight thinks he'll be a great addition to the Justice League.