Bella uses one of the ones that Sherlock gave her and pretends she bought it with the money her father gave her to pick one up. She can always use a little more untracked cash to buy magic things.
Her newt skeleton comes in.
She casts every part of the spell except the final act of will, which she can do any time, anywhere - the spell was effectively on her, to turn her into someone who can at whim destroy the Gem of Amara. She doesn't do it. Sherlock's harmless, and he still - apparently, given that he shows up at school - has the gem.
She can, sort of, trust him. Mint oil and divination lens, useful things.
She's not sure she can forgive him, but she doesn't have to forgive him to not want him to die.
He has a set of gym clothes now, and participates unremarkably in the class. That cuts down on how often he can speak freely with Bella.
But he's still working at the shop, so if he wants to talk to her, he can catch her when she's in to check again for potion-quality sage.
He does mention, on one of these ventures, "The sage is in."
"Still alive." She sighs. "Look, this - vaguely hostile circling thing can't be very interesting for you and I don't want you dead, what would be interesting?"
"I'm sorry, it's just uncomfortable to talk to you knowing you dislike me, and for such excellent reason."
"You weren't thinking very long-term when you accosted me, were you."
"On a number of counts, no," he says. "I also, as I believe I've mentioned, didn't know what effect I was having on you. You seemed to be reacting much as I would have, and I've never seen the threat of death as anything more than an annoying inconvenience."
"Acting like a gibbering incompetent wouldn't have accomplished anything and I had the self-possession available to spend on not doing it. Internally I was screaming. I thought you noticed everything."
"I notice plenty. I'm not a bloody telepath," he sighs. "The insides of other people's heads have always been my major blind spot."
"Thank goodness," she shivers, "that would have me externally screaming in a jiffy. I didn't think I was a particularly good actress, though."
"I could tell you were having a physiological fear reaction but I have those too and they don't mean much to me."
"It wasn't just that. I get that on roller coasters, I get it a little talking to you just now even though I trust my spell more than my gut - I also believed you were likely to hurt me and I'm whatever the opposite of suicidal is."
"You said before that you'd say you were sorry, but you'd be lying."
"Before," he reminds her, "I didn't know how upset you were, or that I cared."
"I hadn't thought about it. The entire chain of reasoning failed to occur to me."
She leans on a wall. She tucks her potion sage into the box from her mother's new laser pointer that she picked out of the trash to pretend it was hers. "It helps that you're sorry."