"My fight was never about that Elise. Why would it be about that? You of all people should know."
Her hand holding the wand was shaking. The sounds of the battle raging throughout the school were echoing into the classroom she had found him in. Bright flashes of spell fire could be seen through the arched windows of the room. And her brother just stood there in that stupid military jacket looking completely at ease. She hadn't even disarmed him. Why couldn't she do this?
She had to do this. Theo's life was on the line and she loved him. Not more than she loved her twin, just differently. Her twin had left her but Theo never had. Theo had taken her in.
"It was always about the mudbloods and blood traitors Harry. They taint our world. When this fight is over everything will be better." Her voice shook when she uttered the comforting rhetoric. Theo would be fine and her brother would probably escape anyway. She would never want to hurt him, not properly at least.
A bemused look was on his face now and a huff of disdain left his nose.
"No Elsy its not. You are deluding yourself again. Like you always have."
How could he be so calm! He hadn't even raised his wand yet. It was like she was not a threat at all to him. Typical Gryffindor.
"But I have to wonder why you are doing this? You surely don't believe that bullshit you just spouted. So, what is it Elsy? Why is this happening? Did I do something to offend you? It's time to be honest for once"
She was silent. Her goals were clear but he kept confusing the narrative.
"I get why you did what you did Elsy. You are in love. What is a few muggleborn in the face of Nott's demise? I certainly would for Daphne."
He looked blatantly curious like he didn't understand what he had done. How could he not know? Her hand wouldn't stop shaking.
"You left me.. YOU LEFT ME!"
"I left you? It was you that left first sister. You were the one that didn't want your embarrassment of a brother around your special friends. You were the one that left to dear Theo's house at the beginning of our third year and left me at Diagon Alley alone."
"You always were running around with that Granger and Weasley! Longbottom as well! Where were you when I needed you? When I was alone in the Slytherin dorms crying? You promised you would never leave me and you did."
Silence for a moment. Only broken up by battle noises. Her hand had finally stilled.
"Elise, I swear you twist reality to suit you. I came to see you every morning but it was too hard for the high and mighty pureblood pandering Elise to be kind to her brother was it not? Her brother that took the beatings for her since her parents died? Her brother that spiked their hateful relative's food with potions so they would be left alone? The brother that always made sure she was fed and warm. Your delusional Elise, clearly Bellatrix is rubbing off on you in more ways than one. "
How dare he mock her! That lazy lilting voice that was always so comforting when she was young just aggravated her now.
"All your rhetoric is pointless anyway as my actions in this fight, this war was never about the causes the dark and light spout. Granger? Weasley? Longbottom? Do you think they ever mattered in comparison to my sister? My other half?"
His eyes glanced around the room for a moment keenly before zeroing in on hers. It was uncanny how closely they resembled each other.
"I needed an efficient administrator and there was a smart girl screaming for acceptance. I needed wands and to make sure our benevolent overseer of a head master believed I was on the page as him, hence Weasley. A family full of able bodied magi to fight on my behalf. Longbottom, a lonely heir that has money to fund my causes when the time comes for just a little of my time and attention. How did you ever get placed into Salazar's house Elsy to not see this? I thought you knew me better!"
Her face shook. Her wand wasn't.
"You cut me off from the Potter Vaults! I was destitute! You locked away my heritage from me!"
He had the gall to look amused and his voice softened. It all felt very dangerous. Surely, he wouldn't hurt her even if a wand was in his face.
"If you think I would let the Potter family magic and gold ever pass into that hands of that wreck of a wizard you call master you have fallen further than I thought. I left you a trust fund when you turned and made sure your school costs were paid. If you expected anything further you were mistaken."
A huge smile eloped his face. She had always loved her brother's smiles in the cupboard under the stairs. Now they just felt dangerous.
"You should have read grandfathers journals better sister. Potters do not kneel. And that's what you are aren't you? A kneeler. Grandmothers memoirs even mention the Black family motto….Always Pure not in blood but intent. You never understood those lessons. I begged you to read them."
A boom echoed from the battlefield distracting her for a moment. An overwhelming force flung her into the far wall leaving her enough time to launch a cutter at his face but not enough time to resume standing. His magic forced her upright and stuck her to the stone.
Wiping the blood from the gash on his face he stalked towards her. Strangely she had stopped being terrified. His and her magic was so similar, so warm, so closely entwined as twins that she could escape if she chose to. Even if his abandonment hurt her it was nice to talk again.
"I am almost glad you will be a Nott soon Elsy. Yes, I kept up with the news of your betrothal. Notts are kneelers unlike Potters, three generations licking the boots of dark lords. Will my niece or nephew be another? You even found the most pathetic Black to mentor under. It would be almost funny if you were not my baby sister"
"You knelt before Dumbledore too. Filthy hypocrite! You dare rant at me for kneeling? You knelt before him the day you walked into Hogwarts! At least I had the courage to go a different path other than you, golden boy."
She wished she could sound a calm as him but instead she came out sounding like Bellatrix.
Suddenly he started laughing.
"Once again sister you never understood why I fought." He held up his wand hand, one of his fingers wore a strange chunky ring.
"This is the wand I took from Albus Dumbledore when I forced a poison down his throat. I never knelt before that man and when this is over I will ensure all of his legacy is ruined."
She was shocked. Everyone knew that Albus Dumbledore was Harry's mentor. She had always found that man unsettling with his piercing eyes. He that had left Harry and her to the Dursleys. And her brother had killed him? What?
"Let me tell you what is going to happen when I walk out of this room Elise. I am going to kill your pathetic master in front of everyone. And when I do the cowardly masses will fawn to me. The light and muggleborn will think I fought for them. Once my relationship to Daphne is announced the neutrals will side will me as long as I pay lip service to the old ways. The dark….well I doubt there will be many dark families in power after this. In a few years I will be Minister of Magic. I will do whatever I want, whenever I want and convince everyone it's for their own good."
The pressure from his magic was increasing and filling the room. Her invisible bonds tightened against the stonework. The noises from the battle outside were getting quieter. He looked manic and feverish. Sweat was pouring off his face and his eyes were lit with excitement.
"All those kneelers will be kneeling before me Elise. This disgusting society left us at the Dursleys to suffer whilst they knelt before Dumbledore. That man could do no wrong in their eyes but we know better don't we sister? That pathetic snake face squibborn outside and his followers will kneel before me too just as they are about to die."
She had always thought that Harry was a bit more stable than her after their ordeals. Always playing the part, smiling and charming whilst still being brash and brave. But at this moment all those assumptions were proven completely wrong. He was completely deranged.
"Both Dumbledore and Riddle are responsible for what happened to us. Those masses out there allowed it. But at the end of all this they will be forgotten and irrelevant. There will be only us left Elsy, us and the wizarding sheep before us."
The magic holding her to the wall was released suddenly and he looked calm. Her wand was still in her hand so she flung out a banisher slamming him into the wall. No shield would work against magic so similar to each other's.
"If you dare hurt Theo in your insane plans nothing will stop me from killing you Harry." The glare on her face had no trace of Bellatrix in it, only the intensity of her mothers.
From his place on the floor he grinned. She felt a force slam into her stomach knocking her down to his level.
"No Elsy. When this is finished I will announce that my sister was playing the long con and passing information to me. Without the sweet brave Elise Potter the war would never have been won. Theo, if he is still alive, will end up taken along for the ride I guess."
With a shrug of his shoulders he stood up and brushed himself off. She felt exhausted but at least she knew her brother still loved her. At least with this plan Theo was protected. She had protected Theo in the same way her mother had protected Harry and herself. Maybe sacrifice was a Potter trait.
"Protecting me to the very end Harry? I don't know how you didn't end up in Hufflepuff." One last quip before they went their separate ways. Her a tragic heroine in the eyes of the wizarding world and he a mad dictator with a vicious callous girl on his arm.
"Don't be silly Elsy, I had to beg not to be put into Slytherin."
End
I noticed whenever Harry has a sibling there is generally a huge power inbalance between him and the OC. If they both grew up at the Dursleys Harry turns against his sibling with Ron spouting garbage. If they were separated the OC is more powerful generally because they grew up in a wizarding family.
If Harry had a sibling I always assumed his motives would be completely different. He would have someone to protect. This Harry is obviously completely different to canon but I liked the idea of them not being able to shield against each other due to mysterious twin activities.
In terms of who is right and who is wrong I dont think either character have any sort of moral high ground. Elise most likely killed people and in Harry's eyes betrayed their parent's memories. He thinks he always gave her time and protected her. Harry manipulates people, kills those who gets in his way and in Elise's eyes abandoned her. Both are unreliable information sources.
This one shot is my attempt at improving my dialogue writing which I am pretty bad at. I wanted a flowing conversation without it being a text dump and I think it works a bit better than my previous stories.
Canon doesn't really matter at this point and the steps leading to the Battle of Hogwarts can be imagined completely differently as the characters are different. My Harry wouldn't have gone camping for example but i hope you could fill in the blanks.