This story is basically canon-compliant up to season 2. Ignoring the business about Joy and Indigo Moon.
"HOW often?" Hecate said, although she had heard Miss Cackle perfectly.
"Once a week." Ada replied. "Isn't it a grand idea? One week our students will go to Miss Pentangle's for lessons in modern magic, the next week they will come here for lessons in the most traditional magic."
"It's really not that far, you know, an easy broomstick ride." Miss Drill pointed out.
"Quite." Ada said. "We begin next week. Oh, I know you don't approve of modern magic, Hecate, but it is the way of the future, and our girls deserve to learn. It will also do them good to interact with other teachers and students."
That night, Hecate mirrored Pippa. They had been talking, occasionally, since their tentative reconciliation after the Spelling Bee, but they hadn't spoken in a few weeks.
"I hear we will be seeing more of each other soon."
"Oh I did so want to speak to you about it, Ada was insistent that we work out the details before anyone else know. You're not cross with me, are you darling, you look a bit cross."
Hecate considered whether she was cross that Pippa hadn't mentioned it. Perhaps just a little hurt. "I am merely unsure of the educational benefit to my students."
Educational benefit or not, it absolutely had an effect on their relationship once it began. They got into the habit of sharing their Friday evenings at whichever school they had been at. The students would leave after dinner, with the rest of the faculty, but one of them would usually stay behind well into the evening. Hecate could have sworn last time Ada gave her a wink, which she studiously ignored. She was sure she had no idea what that could mean, she and Pippa were merely old friends getting reacquainted. The girls had to fly back on their brooms, but she and Pippa were easily accomplished enough to transfer between the schools directly, so there was not as much of a rush.
The girls of Cackle's academy were primarily focused on the social benefit to this new exchange program too.
"They are a COED school!" whispered more than one girl, upon hearing the news.
The excitement only grew when it was announced that Pentangle's would be hosting a formal ball, and naturally, they were inviting the students at Cackle's to join them. A formal ball took on different meaning when there were boys involved – suddenly the idea of dates was a concern. With there being significantly more girls than boys, this started to worry the girls at Cackle's.
"It's a spell that reveals the name of a boy who has a crush on you." Bea grinned. "Heard one of the fourth-years talking about it."
"I don't know if this is a good idea, isn't it kind of like a foresight spell?" Clarice worried.
"I think it's okay, because it's about now, right? It's a bit complicated though, maybe we should ask your sister to help us, Syb."
Somehow this ended up spiraling, and about a dozen second and third year girls were crowded into Mildred's room, with Ethel cautiously hoarding the potion she had carefully made.
"What if nobody has a crush on us?" Felicity asked quietly.
"If nobody does right now, it will show you the name of the next person who will." Mildred answered.
"Assuming someone is ever going to have a crush on you, Mildred Hubble." Ethel said, managing to sound very much like HB as she said her classmate's name.
The first two girls who sipped the potion saw the names of boys they knew from Miss Pentangle's. One was pleased, the other less so. But it only took until the third person for the real drama to start.
"Alice?" Posy, a quiet third-year, read out hesitantly.
"Ooh, I know an Alice at Pentangle's, you remember, kind of tall, blond hair?"
"But she's a girl!" Posy said, disappointed.
"You DO know girls can like other girls?" Felicity said haughtily.
"Well they shouldn't. My mum says it should be against the Code." Ethel said rudely.
"I know they can, but I don't fancy girls." Posy pointed out glumly.
"Well she must. Don't worry, it's not like it says this is the only person who will ever like you." Mildred assured her.
A few more girls took their turns, then it was Sybil's turn.
"C-Clarice."
Clarice, who was sitting next to Sybil, went white as a sheet. "What? I don't. I mean, I'm not. I don't…" she trailed off. Did she? She hadn't had a crush on a boy yet, but she figured she was still young.
Everyone was staring at her. She got up and ran out of the room.
"I can't believe it, she is such a talented witch. How could she be queer?" Ethel said unkindly.
"Ethel! That's not nice." Felicity called her out. But some of the other girls looked like they agreed with the older Hallow. Sybil, for her part, still looked shocked.
"Come on, Sybil, mother wouldn't want you sitting with a dyke like her." Ethel said, pulling her sister's arm. "Come sit with us."
HB was walking past the table as this occurred.
"Ethel Hallow." Her voice rang out throughout the room.
"Y-yes, Miss Hardbroom?"
"I hope you have some explanation as to why I just heard a vile slur come out of your mouth."
"Well because it's true, Miss Hardbroom. Clarice is queer and she's got a crush on my sister, and I don't want her anywhere nearby."
"I don't even.." Clarice tried to speak up, tears in her eyes.
"She's my FRIEND" Sybil said at the same time.
"You see it was a spell" Bea tried to help.
"SILENCE!" Hecate boomed. "Ethel Hallow, detention for a week. You three, see me during your next free period." She indicated the trio of second years. She gave them all a glare before continuing on to take her seat at the teacher's table.
"You know, I've heard more talk about girls being gay in the past two weeks than I ever remember." Dimity said as Hecate took her seat. "Funny how exposing them to boys occasionally seems to have brought this on."
"One of them mentioned a spell. No doubt something to do with this." HB grumbled. "Modern magic indeed."
"Hecate, there's nothing inappropriate about two witches together." Dimity said tentatively.
Hecate's eyes flared. "I did not say there was, Miss Drill."
"Okay, just thought, er, I was making sure we were all in agreement." The other teachers all nodded. "I have been thinking of asking Minerva Moonshine out, myself." She continued. "It's so hard to meet people with our jobs, it's been nice getting to know the staff at Pentangles."
"Is that the spell science teacher at Pentangles? She does seem like a nice one." Ada commented.
"Remember Teresa and Katie, graduated a few years ago? They were always so cute. I heard they had a baby." Miss Bat said somewhat abruptly.
"Teresa and Katie graduated nearly fifteen years ago, and that baby is due to apply here next year, actually, and another one in a few years." Ada said with a smile.
"Oh! How time does fly."
"Ten pages on the history of gay rights in the witching community." Hecate said, materializing a stack of books on Ethel's desk.
"But Miss Hardbroom, surely a traditional witch like yourself doesn't support such…modern ideas. Witches and wizards complement each other, it's unnatural otherwise."
Hecate leaned down over her pupil. "I do not know what hate-filled bigotry your parents have been teaching you, Miss Hallow, but in this school we accept everyone for who they are. You are in fact completely wrong about my views on this subject, and hopefully one day will come to realize how wrong yours are. I cannot necessarily change your mind, but I can expose you to different ideas on the subject. And I can make you act kindly to every student in this school, including the gay ones. Do I make myself clear?"
"Yes Miss Hardbroom." Ethel deflated.
"Excellent. Now get to work, I have work of my own to do."
"Well you see, Miss Hardbroom, everyone was wondering how to tell if a boy liked them, and I found this potion, it tells you the name of someone who has a crush on you, or the next person who will. So we all took it, you see, and when Sybil did, well, it said Clarice."
"But I don't, Miss Hardbroom, I don't have a crush on anyone." Clarice insisted.
"I see. And did anyone else's name appear, that I should be worried about being bullied for this?"
Bea shook her head. "Not here, anyway. A girl at Pentangle's likes Posy, seems. Posy doesn't like her, though."
Hecate studied them. "And this potion, is it gone?"
The three girls looked at each other.
"Well?" Her eyes bulged out, irritated at the girls' evasiveness.
"There's some left, we were going to let some of our friends at Pentangle's use it, but after all this fuss we weren't sure." Sybil admitted.
"Sybil, go and fetch it. Bea, you are excused. Clarice, stay here a moment."
Sybil and Bea left, leaving Clarice looking terrified.
"Miss Hardbroom I swear, I don't know why it said that."
"Clarice, it seems the potion may have exposed something you were not yet aware of yourself. I am dreadfully sorry for that, because everyone deserves to find out their interests in their own time, and more importantly, come out on their own terms. I am sorry your friends' antics have stolen that from you."
Clarice looked down. "I don't think I've had a crush on anyone yet."
"That is completely normal. But Clarice, you need to know, if it is witches you fall in love with, or if you like both witches and wizards…that is all right."
Clarice looked up at her, tears in her eyes. "But Miss Hardbroom, I don't know any witches who like other witches. And everyone is being so mean."
Hecate took a deep breath. "You do, in fact, know at least one witch who likes other witches. Me. I would appreciate if you did not spread this knowledge around, however. It's not that I am ashamed, but I do not like students gossiping about any aspects of my personal life."
"You do?" Clarice looked at her with wide eyes.
Hecate nodded. "I do. Always have. I won't lie to you, it hasn't always been easy. If you ever need to talk, I am here. And if anyone else calls you names, or anything else, you let me know. I have my eye on Ethel Hallow. What she said was unacceptable and will not be tolerated."
"Okay. Miss Hardbroom?"
"Yes, Clarice?"
"Can I um, tell Sybil and Bea? If they promise not to tell anyone? Only I'm not good at keeping secrets from them."
Hecate sighed. "Yes, I suppose so. Do try not to tell the whole school, Clarice."
"I won't Miss Hardbroom. Thank you Miss Hardbroom!"
Sybil came bursting back in at that moment, with a large vial of potion. She handed it to Hecate and then the girls scampered out of the classroom.