There isn't just the smile..... there is a change in the music that goes from sad to.... dark? Menacing? If I knew more about music in terms of minor and major chords I might be able to better explain or describe..... but the musical tone changes right at this part and I don't think it's on accident. Nothing Neil Gaiman does is on accident.
For 'reasons', Ellie has been transferred to Gotham Academy under the guise of living with her guardian Vlad Masters but she's actually living with Dante, Danny, and Jazz.
From the moment she arrived, she had become rivals with Damian Wayne in everything from academics to sports and even the arts.
They wouldn't admit it but they were having fun. Having a rival who's always trying to one-up you, forcing yourself and each other to become better, more extraordinary. (It made a great distraction from their complicated home lives.)
But somewhere along the line, something had changed.
After a debate competition that was held at the school, Damian couldn't help but gush talk about this girl, his friend, Danielle Masters, and how cool and competent she was, and how she was the only person in the school worthy enough to be friends with him. (Awe baby's first crush!) But, ah, Dames, what's an ectoplasmic being and how are they not sapient or sentient?
On the other hand, Ellie is livid. She had Dan buy her a punching bag just so she could put Damian's face on it. She thought he was her friend! Turns out he's just another anti-ectoplasmic being supporter. She tries every day, to go to school, talk to him, and pretend everything is normal. But every time she sees his face and perfect smile of victory, her blood boils with a cold icy rage. (How dear he proclaims so proudly the ghosts are not truly living beings!! Just because we are dead doesn't mean we do not live on.)
Good thing Danny knows how to make portals now! Because when she gets home she's gonna go ape shit.