"We killed two Dementors! And Feral can do a glowy person now!"

"That is interesting."

"He had to get a good look at one, though. And I don't think that can be it because probably plenty of people look at Dementors."

"What is your theory, then?"

"I don't know exactly. Some combination of - feeling like I do, or like Feral does because apparently that counts - about them, and - getting what they are?"

...He waits for her to elaborate.

"They're a death thing, about death or pieces of it or something," Bella explains. "They aren't okay the way death isn't okay. I think the animal Patronuses are sort of going - 'la la, you can't scare me, animals cannot comprehend cessation of existence'. And the glowy persons are about - hope instead of distraction."

"Feral didn't seem to think it made all that much sense when I explained it but he put it together after he got a look at the first one we found. The second one we just strafed."

"I am not sure I understand," says Sherlock. "And the parts I understand, I am not sure I like."

"What's not to like? I mean, regular Patronuses still work for doing regular Patronus things."

"I am not very good at hope," says Sherlock. "I am even worse at - personal illusions, of the cognitive rather than the magical kind. If your theory about the animal Patronus is close to the mark, then knowing that, I don't think I will be able to cast one."

"...I could be completely wrong though, I never even did an animal one..."

"You could," he says.

"So - I guess you don't - feel like trying one now, but - I hope I didn't break yours or something, even animal ones are useful, maybe I'd better not tell anyone else my theory."

"I - I broke Sherlock's Patronus. I was explaining it to him and - he can't even get an owl now, let alone a person."

"...that's not good," says Feral. "Wow. How'd that work?"

"I don't know!"

He hugs her.

"But I guess I'd better not try to explain to anyone else, huh?" mumbles Bella into his shoulder, hugging him. "You were lucky, Sherlock wasn't - I don't know what the odds anybody else will be are. I don't want to break Tony's or anybody else's. Regular Patronuses are better than nothing."