This plot came out of my mind reading an other fanfic so I don't how it will turned out. Some events and the timeline are going to be changed.

This is a first for me so I do not know if my uploads are going to be steady.

English is not my first langage, corrections are welcome.

Disclaimer : the canonical characters belong to J. K. Rowling, as does the Wizarding World and all associated concepts.

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They were doomed. Mary thought while running inside Hogwarts' corridors, trying to reach the great hall where she knew there would be others students.

She heard the mad one laughing, she was close - too close from the sound of it. Hogwarts was invaded by death eaters, and their only opponents were children. Nothing good could come out of this fight.

Breathless, she stopped behind a pillar. She took time to check for any noise while she pushed her black, wavy hair out of her face. When she was certain the only sound she could hear was her own heart pulsing in her ears, she started running again.

Finally, she thought has she pushed open the dining hall great doors. She didn't have the time to checked on the students present before she felt and smelled Harry's familiar embrace.

"Mary ! We were so worried ! I think McGonagall is dead, we don't know where Dumbledore is, and ... and ... the death eaters are everywhere ... we don't know what to do." Mary gently pushed back Harry's embrace but gripped his hands. She looked into his bright green eyes, revealing his fear and despair. Her own grey eyes mirroring this state of mind.

"I know, I saw them marching towards the castle and breaking the fence. Is everyone here ?" Harry knew instantly who she was referring to, their chosen family, the friends they made the past few years. Mary was a shy and wary girl, wariness brought by her years growing up in an orphanage, not all his friends were hers but all hers were his.

She let go of Harry's hands to have a look at the great hall, her eyes already searching for her friends.

The hall was lacking his usual warm atmosphere and bright colours brought by the decorations or the student's clothes. The room felt cold and old, the empty walls and tables were a dull mass of grey and brown.

Small noises could be heard from the right and the left. Students were bundled according to their house or kinship.

"Yes, Fred and George are just over there with Luna and Neville. Hermione and Ron too. Slytherins are over there." Harry's responded while taking Mary's hand to make her follow him towards their friends at the front right side of the room. His hand left hand showing a group of slytherins the opposite way, at the front but on the left side.

Mary briefly glanced towards the Slytherins before analysing her friends. Fred and George looked unharmed but were tightly clutching their wand. Luna was using healing spells on Neville. His leg left seemed to have been cut. Hermione taking care of Ron whose left side of the face was covered in blood.

A breath of relieve escape her lips. Her friends were alright and safe, for now.

"What do we do now ? We cannot wait here. Most of them have been students at Hogwarts, they know the castle. Besides, this room is an obvious rallying point. They are going to burst in soon enough." Mary exclaimed with she hopes a calm voice. Everybody, was already panicking, more fear would just cloud her thoughts.

"Damn right, there are probably in the hallways...

...making a fun of destroying anything in their way." said George and Fred, eyes darting and forth between Harry and Mary.

Harry pursed his lips before replying, "I was thinking of Hermione's time turner. We could use to go back only a few hours ago. Make sure to have a plan and Hogwarts empty before the attack."

Hermione raised her head and silently nodded to Harry.

"In the meantime, we could ask the seven years to apparate the youngest as a precaution ? The wards and charms protecting the school have been destroyed." Proposed Mary. Going back will not save the students presents in the great hall in this timeline.

"Yes, Fred, George, could you see with the others 7th years of they would be okay with Mary idea ? The can also apparate the others fifth years. Hermione, Ron, Mary and I will use the time turner." Harry was already reaching Hermione when they suddenly heard a muffled bang seconds before the doors of the great hall burst open.

Umbrage was standing at the entrance along with a few death eaters. The toe like lady gave a throat-clearing cough and giggle before saying "Well, I thought the Ministry pass an act against students gathering. It seems some of you did not understand the instructions. My dear counterparts will be in charge of your punishment."

A shocked and horrified expression could be seen on the students. Some shrunk on themselves as if wanting to disappear.

Harry's eyes were fixated on Bellatrix Lestrange, situated next to Umbrage, and looking as crazy and please with herself had ever. His hand was discreetly for his wand in his pocket. The twins were stopped in their way towards other groups of students, trying to decide between fighting and move on with their plan to apparate. Mary's round grey eyes were wide open and her bow-shaped lips ajar and her attention on the heavy gold locket glittering with a green stone Umbridge was wearing.

Bellatrix was the first to make one a move and then hell broke loose ; everyone started to cast spells to attack or defend themself.

The twins and the few seven years Slytherins were successful and the hall was now voided of fourth years or younger. They came back for Neville and Luna and the fifth years Slytherins.

Mary was taking advantage of the chaos to discreetly approach Umbridge. She was so focused on the locket and briefly disturbed by Harry scream her name that she didn't one of the death eater spot her and carefully monitoring her.

All the others were now a small group of students in the middle of the room, Harry, the twins, Nott, Flint and Greengrass were shielding the small groups.

"Hermione, hurry up, the time turner." Harry pressed. He made a motion towards his left and right side. "George, you apparate Lovegood. Fred you apparate your brother, he cannot go with us. Flint you take Longbottom. Greegrass, your sister. Nott, you make sure there is no one left." He continued before shouting "MARY, we have to go !" His scream did not distract the concerned party from her task.

Nevertheless, his scream showed all his fear and followed seconds after by Bellatrix's crazy laughter. Pleased with the situation and not caring about the age of her preys she continued to hex the group. She was supported in her attacks by Carrow, Beurk, Fawley, Rowle, Yaxley.They were students, they were going to get tired and their protection spells would not last long and then she would have her fun.

Everything seemed to happened at the same time.

Hermione tugged Harry's jean, the time turner ready in her hand. Umbridge satisfied by the situation in front of her eyes, was taken by surprised when Mary out of nowhere locked her hand on the necklace she was wearing. Her eyes grew dark in a second, she raised her wand at Mary while saying "I despise children and I loathe mudblood. Diffin..."

Nott hexed Umbridge with a disarming charm while Harry and Hermione were now both in the center ready to use the time turner.

At the same time, one of Weasley twin protection spell broke and the death eaters' hexes touched Hermione and her time turner. The time turner chain was broken and it started to move on its on. The seventh years tried to apparate with their assigned protégé but felt sick by an invisible flow.

Simultaneously, seeing Umbridge was disarmed and the young group disappeared in a sand tornado, the death eater monitoring Mary approached her. She locked eyes with him, scared, getting that locket was after all a bad idea she thought. She heard him click his tongue and knew this death eater was Evan Rosier. "Because this friendship never died" she heard him say before feeling his foot on her rib cage and felt herself be violently pushed in her friends' direction where she too was sucked by an invisible tornado.