The days shorten as the end of October creeps nearer. The air is chilly, but it can't compare to the cold of the cursed ice. I doubt I'll ever feel as cold as I did last year.

Today is the last day of the month, Halloween. More importantly, our first visit to Hogsmeade is in three days. All week, excitement has been building in the third years. Rowan has taken to reading us passages from a book titled The Complete History of Hogsmeade. It contains everything from the founding of the Three Broomsticks to wild rumors about the Shrieking Shack. Ben is terrified of the Shrieking Shack, but he's excited to visit the Three Broomsticks, which is famous for its Butterbeer. Tulip, of course, is already planning a visit to Zonko's, the joke shop. "I need to replenish my supply of Stink Pellets," she says. "And they're coming out with a brand-new type of Dungbomb!"

I half-listen to her and Tonks raving about new prank ideas as we walk outside to the greenhouses for Herbology. Filch is going to be busy after we return from Hogsmeade.

Penny trails behind us, talking to no one. She's been quiet and distant since the beginning of the year. I slow so I'm walking next to her. I haven't pressed her to open up, but I try to stay near her, in case she ever wants to talk. I hope that she opens up and tell us what's bothering her soon. She shouldn't keep her sadness to herself for so long.

Today's plant has purple flowers and big pink pods. "Three to a pot," Professor Sprout instructs as we enter.

Penny, Rowan, and I gather around one of the plants. Alana joins Tulip and Tonks.

"Today we are working with Puffapods," Professor Sprout says once everyone has found a group. "The seedpods contain beans that can be used in several healing potions. Madam Pomfrey's supply is running low, so she requested that we work with them today."

She shows us how to remove the pods. She grips the sides of the pod and pushes her thumb through the top, causing several beans to fall into her pail.

"Please be careful when releasing the beans," Professor Sprout warns. They will flower as soon as they come into contact with an earthy surface. One year so many were dropped that I had to cancel classes while I got rid of them."

Rowan glares at Tulip and Tonks, as if warning them not to get any ideas. They look back at her with wide eyes and innocent expressions.

"Miss Haywood, if you would kindly pass out pails to everyone, we can begin," Professor Sprout says. I wonder if, as Penny's head of house, she knows what's bothering her. I'll have to talk to her after class.

"Yes, Professor Sprout." Penny walks over to a table with rows of pails. She reaches for one, but before she can grab it, some sort of dusty cloud rises from it. It coalesces into the shape of a large wolf, snarling and showing its fangs.

This isn't a regular wolf, I realize. Its eyes are too human, its snout too stubby. The end of its tail has a tuft of gray fur. It's a werewolf.

Penny screams, high and panicked. She seems unable to move, rooted in place feet from a snarling beast.

Everyone moves backwards, pressing against the door in an attempt to get as far as possible from the werewolf. My brain struggles to make sense of the situation, finally realizing that a werewolf can't appear in broad daylight. But then what-?

Before my confused brain can make any sort of hypothesis, Professor Sprout pulls out her wand. "Don't panic!" she instructs, even though it's clearly futile. Everyone is already hysterical. "This is not a werewolf," she continues, pointing her wand at the creature. It turns to face her. "Riddikulus!" she shouts. The werewolf shrinks, becoming a small toy, which disappears in a puff of dusty fog without a sound.

"Boggarts," I whisper. "Not fire. Boggarts." I attract some odd looks, but I ignore them. There's no doubt in my mind how this boggart appeared. Someone tampered with the second vault.

I put this thought out of my mind. Later, I can worry about finding the vault and breaking the curse. Right now, comforting Penny is the most important thing.

Everyone else is leaving the greenhouse, but Penny is still frozen in place. Her screams have given way to sobs, and tears are streaming down her face.

I push through the other students to join her. For a moment, I just stand there. I don't know what to say. I should probably ask if she's okay, but she clearly isn't. "Do you want to go to the Hospital Wing?" I ask instead. "Madam Pomfrey can give you a Calming Draught."

Penny shakes her head. "No," she says with a sniffle. "Let's go to the Room of Requirement. I need to brew a potion."

I walk with her to the third floor. I try asking her what she wants to brew, but she doesn't answer. Should I be letting someone so fragile brew an unknown potion? But what other option is there?

A wooden door appears in the middle of the previously-empty wall. Penny opens it. I follow her through. I've visited this version of the Room of Requirement just once before, when Penny brewed Fire-Breathing Potion last year. The room resembles Professor Snape's classroom, although it's smaller and better lit.

Penny selects a cauldron and starts filling it with ingredients. Lethe river water, valerian sprigs, standard ingredient, mistletoe berries…

"Penny," I say hesitantly. "Are you brewing a Forgetfulness Potion?"

"Yes," she says without looking at me. She pours two drops of the Lethe river water into the cauldron.

I wait for her to finish the first part of brewing. The potion has to sit for an hour before she can move on to the next step. She'll have to talk to me then.

"Why? What do you want to forget?" I ask.

"You don't need to know. After I drink this potion, I won't even know." She pushes the mortar towards me. "Crush this, will you?"

I grind together the mixture of herbs and mistletoe berries. There's no reason Penny couldn't do this herself. She only gave me this task to make me be quiet.

I decide not to push her any more. I'll ask about the potion's purpose again when it's complete. For now, I simply sit in silence.

Penny dumps the contents of the mortar into the cauldron and finishes the potion. She fills a bottle with the orange liquid. A few drops spill onto the table.

"Will you tell me what this potion is for?" I ask again.

Penny sighs. "I suppose I should," she says. "Remember how my boggart took the form of a werewolf?"

I don't answer, assuming the question is rhetorical. We saw the boggart an hour ago. How could I have forgotten?

"It wasn't just any werewolf," Penny explains. "I live in London, but every summer my family goes out to the country. I had a friend up there… a Muggle… her name was Scarlett."

With a pang of sadness, I think of Nola. I have a bad feeling that I know where this story is going. I dread hearing the end of this story, but I have to. I'm Penny's friend. I can't shut her out and leave her to drown alone in sadness.

"We went for a walk last summer, just before I came back to Hogwarts. It was the night of a full moon, and we saw a werewolf. Scarlett didn't know what it was. She was fascinated by it, and she convinced me to follow it and see where it was going."

Penny lets out a choked sob. She ducks her head, unable to look at me. A tear rolls down her face, dripping into the rest of the Forgetfulness Potion. "I had my wand. I thought we would be safe… even if I had to beak the International Statute of Secrecy, I could protect her."

She breaks off, sobbing uncontrollably. I walk around the table and put my arm around her. I don't need to say anything. All she needs is a comforting presence.

Penny puts her head on my shoulder. I can feel her tears soaking into my robes, can feel her shaking beneath my arms. I rub her back soothingly.

Finally, Penny sits up. "I'm s-sorry," she says, She sniffles and wipes away the last of the tears. "Just- just let me finish. I had my wand. B-but when the werewolf saw us, I froze. By the time I found the courage to do something, it was too late for Scarlett." Penny looks from me, to the bottle of Forgetfulness Potion, then back to me. "She's dead because of me, Celena. It hurts too much to remember. I can't carry this pain any longer. I need to forget."

"I know how tempting it can be to forget painful memories," I say. When we learned how to brew this potion in first year, I considered drinking it, to forget Jacob. "But you have to be strong. For that one sad memory, there are so many happy ones. You can't forget Scarlett. It's not fair to her. And what if you forget more than you intend to? What if you forget who you are?"

Penny lets out another sob. She places the bottle on the table.

"Losing someone hurts,' I say quietly. "Scarlett's loss will always leave a hole inside you, but you can find a way to work around that hole. I know you can. Because you're strong, and because you have us. We're your friends. We can help you."

"I should have told you earlier," Penny admits. "It felt good, telling you. Thanks, Celena."

I give her another hug. "We're your friends. We'll always be there for you."

Always… The word is a promise I'm not sure I can keep. What if something else happens to Penny and I'm not there to help? Once, I thought Jacob would always be a part of my life. I thought I could rely on him for the guidance that older brothers are supposed to give. Obviously, that hasn't been the case. My life has taught me that promises are easy to make, but hard to keep. All I can do is promise my friendship, and hope it isn't a lie.