Y/n pov:

Today is Halloween and I was sitting in charms class next to Neville. We were performing the levitation charm wingardium leviosa on some feathers provided by professor flitwick. I look over at Hermione and see her arguing with weasley about the spell then showing him how it's done. I help Neville get it right on his fifth try before class ends. Lily and I are walking behind Ron and Harry with Hermione between us.

Ron: she's unbearable and bossy no wonder she doesn't have any friends!

Harry laughed at Ron's comment as Hermione runs past them and I chase her till she reaches the girl's restroom and I stop outside the entrance of the restroom.

Y/n: Hermione! Ron is lying because you have me and Lily as your friends.

Hermione: just leave me alone for a bit y/n! Let me have a some time to myself for a while.

I walk away to the great hall for the Halloween feast. As I enter lily approaches me with a worried look.

Lily: Is Hermione ok? Where is she?

Y/n: she's ok. Hermione is in the girl's restroom crying still but it might be a good idea if you go talk to her so she doesn't miss the feast and so she knows that she really does have friends who care about her.

Lily: that's a good idea y/n. I'll go talk to her.

I watch lily run off to find Hermione and I sit next to Dumbledore and I notice quirrell is missing which is weird since he's always there before me so I shrug it off as he's being careful not to get pranked on Halloween. As everyone is enjoying their food the doors open and quirrell runs in scared.

Professor quirrell: troll in dungeons! Troll in the dungeons!

He faints and everyone is panicking till Dumbledore yells silence.

Dumbledore: prefects lead your houses to their common rooms.

I look at Dumbledore like he's stupid.

Y/n: are you dumb? The troll is in the dungeons so you are leading them to slaughter! Slytherin stay in this room!

The Slytherin table looks at each other in relief of not having to face the troll. I get a feeling Hermione and lily are in danger and teleport to their location.

Lily's pov:

I enter the girl's restroom and go to the stall Hermione is in and knock.

Lily: Hermione can I come in?

Hermione: you heard what Ron said about me.

Lily: yeah but it's not true y/n told me to help you since you are missing the feast and because he can't come in here to comfort you.

Hermione opens the stall door and hugs me before making a disgusted face.

Hermione: what's that smell?

Lily: I don't know.

We look to the door to see a mountain troll standing there. It swings its club at us and misses destroying the stalls and swinging the club again as I push Hermione out of the way as I get smacked into the wall breaking my arm and hitting my head on a sink. I see a fire appear behind the troll before passing out.

Y/n pov:

I exit the flame portal and see a mountain troll standing over Hermione and lily and send a cutting spell at it to distract it causing it to swing it's club in my direction breaking some mirrors as a few pieces flies towards Hermione which distracts me for a second.

Y/n: Hermione get down!

Hermione gets down a little late which causes the glass to cut her forehead and cheek a little bit. Harry and Ron enter seeing me crash into the wall next to them but seeing my friends hurt I shift in my Carnotaurus form and charge the troll. I bite the arm with the club causing it to let it go as I got the nerves and muscles to make it have its hand closed on the club to open. I smack it in the chest with the tail then bite at the neck missing. Hermione crawls over to lily to check on her as I bite the troll on the leg and pull it off it's feet as Ron uses the levitation charm on the club dropping it on my back as I ripped out the throat of the troll. I growl at him in anger causing him to yelp in fear as I shift back to normal to check on Hermione and lily. I let the Carnotaurus eat the troll when the teachers enter.

Professor McGonagall: what happened?

Hermione: it was my fault professor. I thought I could take the troll on my own but I was wrong Lily and y/n came to help get me to safety but lily got hurt and y/n got angry that we got hurt so he turned into that Carnotaurus which he used to fight it. Harry tried to convince me to move but I was worried about lily and Ron dropped it's club on y/n.

Y/n: prowl at my side.

Prowl appears next to me from a ball of fire leaving my body and me and Hermione put lily on prowl's back and head towards the teachers.

Professor McGonagall: well then five points from gryffindor miss granger for poor planning and mister weasley three points from gryffindor for hurting another student, mister potter five points to gryffindor for helping a fellow student in danger and miss potter six points to Slytherin, gryffindor, and ravenclaw for trying to protect a fellow student.

Harry: why does Slytherin, gryffindor, and ravenclaw get points from my sister.

Y/n: because she is in all three of those houses stupid.

I snap my fingers at the troll corpse and the Carnotaurus and they get teleported to the my common room. Me and Hermione take lily on prowl's back to the hospital wing.