Okay okay if you insist, sheesh.
The thing about most batkids band AUs is that they either 1) exclude half the family or 2) try to cram everyone onstage. Not that there's anything necessarily wrong with the second one—a number of real bands work that way—but in this case, it feels forced and becomes a case of too many cooks in the kitchen. So I'm gonna give you my take, because this is literally my world.
We'll divide the roles into three groups: the ones in the limelight, the behind-the-scenes musicmakers, and the non-musical crew. All are equally important, so don't take this as favoritism or me sidelining anyone. Also, keep in mind that none of these are mutually exclusive. A lot of roles are cross-disciplinary and people go back-and-forth or fulfill multiple roles.
Let's actually start with the crew. These are the non-musicians that, realistically, would be a full crew of people, but let's just ignore that for now.
Tim would be all over the visuals. Yes, the music is first and foremost, but things like album covers, promo material, and merch design are just as important—the merch is actually a huge portion of revenue in the industry. Yes, you could argue that Damian is good at drawing, but this is really about visual arrangement, and who better than a photographer? I can see him drafting different designs and playing with Photoshop to capture the band's vibes. I could also see him doing something adjacent like concert photos/recording or editing music videos.
Harper isn't the only one good with gadgets, but I'd argue she has a unique perspective when it comes to engineering, making her perfect for practical effects, such as in music videos or onstage. More importantly, though, she can think on her feet and come up with the exact fix before the problem unfolds. This is especially important during live shows, where a minor mishap can quickly spiral. I think that her knowing her limits can actually lend to her getting creative and having more fun with confetti cannons, pyrotechnics, or animatronics if she so chooses.
Now to the second group: the ones behind the music.
Damian would be the key songwriter. Being a classical musician means that he'd have a solid grasp on composition and music theory, and all songwriters play an instrument of some kind. But that's not the main draw. Damian comes from two different worlds—the League of Assassins and Gotham. I think that would reflect in his songwriting style, combining tradition with modern influences. It would additionally reflect the band because everyone in the batfamily has similarly distinct before-and-after stages of their life. Also, I don't think he'd enjoy performing outside a narrow set of contexts, and a rock band wouldn't be on his list.
Duke is a poet, so I think he'd make sense as a lyricist. In canon, he and Damian work really well together, which is an important part of the process. The key to good lyrics, though, is knowing who you're speaking to. Duke takes his time to understand each batfamily member, so even if he hasn't lived their experiences, he can translate them into song. And although music is about self-expression, there is still the audience to consider. Duke has his ear to the ground. He knows what people care about and what needs to be said, and he's also not afraid to call out the powers that be.
Barbara would be a good producer, and not just because she's tech-savvy. As Oracle, she is coordinating a ton of moving pieces without losing her cool. She has to keep track of tiny details without losing sight of the big picture. As a librarian, she has to catalogue meticulously and often do the same repetitive tasks. Being a producer is essentially a combination of the two. A lot of people would get overwhelmed with the toolbox a producer has, but I can picture Barbara taking one look and knowing exactly what to do.
Finally, we have the band itself.
Dick would be on lead guitar. And yes, I know every AU puts him in this role, but there's more. Canonically, he plays the guitar, but I think his personality is ultimately what would lend to his artistry. He'd have no problem taking center stage with guitar solos and would have the most memorable riffs. Also, he's not afraid to try new things and go big. Like, Discowing, much? Now imagine that energy channeled into experimenting with pedals, distortion, or alternate forms of picking and tuning. (EDIT bc I forgot: Dick would totally troll people with the Buddy Holly riff.)
Jason would be the bassist. Now, a lot of people view bass players as simply secondary to lead guitarists—some musicians even think this and it's kinda annoying. The way I see it, the bass and lead guitar fill in each other's blanks, and you could describe Jason and Dick's sibling relationship the same way. Jason isn't outwardly flashy like Dick, but he likes to show off on occasion, which a good bass hook allows for. Dick and Jason's dynamic is also built on contrast, which I can see Jason accomplishing through the right harmony or countermelody.
Cass would be the drummer. She is highly observant and physically coordinated, so the drums would come as second nature to her even when all four of her limbs are doing completely different things. Cass doesn't need to be in the spotlight for everyone to see her importance, and like a mission, a song wouldn't be as effective without her. Also, speaking as a drummer myself: we're actually the ones in charge—if I feel like playing at 200 BPM, the song is now 200 BPM.
And lastly, we have our vocalist: Steph. The difference between a good vocalist and a great one is confidence. Steph brings that. She's confident, upbeat, and can turn the energy of a room. A good stage presence and knowing how to interact with the audience is important—reading the room, getting them excited, and injecting humor or seriousness into the right spots. A lot of vocalists also play another instrument (the synth seems to be popular), so I can totally see Steph doing that as a way to augment the sound and have fun.
