Bella is about to turn thirteen! This is exciting.
The glowy person doesn't do anything.
"Well, I guess that won't work." She dismisses the glowy person.
"Suppose so. Summer project, maybe, I will read up on United Kingdom wizarding law. I wonder if it is even technically illegal to destroy their dementors."
"Hmmm. I should probably practice on wild ones first, anyway, I'm not sure how well Glowy Person holds up against groups of Dementors or anything."
"Unless someone notices the wild ones are disappearing and gets nervous about Azkaban."
"Well, I don't know, but I bet someone notices when souls start getting sucked out, maybe there's someone keeping statistics who'd notice a drop."
"They might get nervous for other reasons. If they thought the Dementors were, I don't know, collecting somewhere they didn't track and being obvious."
"They might ask the Azkaban Dementors. They have some way I don't understand of communicating with them, I don't know if other Dementors can tell what just happened to this one." She gestures at the cloak. "Speaking of which I don't know how to dispose of that."
"Yeah, okay," she says, and she holds her wand ready to put out the fire if it threatens to spread to the trees.
Bella rummages around in the picnic basket. She finds some chocolate cookies that they didn't get to. She presses one into Sherlock's hand, takes one, offers the others to Feral and Tony.
Tony eats her cookie with one hand and hugs Sherlock with the other.
"Are you okay? Should I bring back my glowy person to pet you more?" Bella asks Sherlock.
"I will be fine," he says, snuggling Tony. "It was much worse last time."