Harry was sure in that instant they were both wondering the same thing.
This is such a dark moment and I’ve never seen it talked about before!?!
The suggestion that Harry ‘I will turn this broom around to save Malfoy even though this room is filled with cursed fire and I have a Horcrux to destroy’ Potter might not have rushed to the rescue of Vernon Dursley is… woah.
It says a lot about the neglect and abuse Harry suffered with the Dursleys that he isn’t at all sure he’d want to rescue Vernon. Dudley does redeem himself. Harry has occasional moments of connection with Petunia, like in OoTP when he tells her Voldemort has returned. But Uncle Vernon? There is never, ever a moment of kindness or understanding between them.
MORE than that, Vernon suspects that Harry wouldn’t rush to his aid if he were captured. Does he assume this is because Harry has no interest in helping ‘his lot’?? Or because he knows, deep down, that his treatment of Harry really has been appalling and Harry has no reason to love him or worry about him??
It’s just a tiny little moment between these two characters, but it says so much about their (totally awful & dysfunctional) relationship. Lastly, I bet this is the only moment in the series where both Harry and Vernon are wondering the same thing simultaneously.