AN: MASSIVE spoilers for 5x06 so if you haven't watched it, be warned. As much as I love the idea of Dark!Gwen how it happened and what happened has really annoyed me just my heart being torn out and I'm upset and goddammit the fact I seen it coming makes it worse. Some of this is what I think may happen after episode 7 (going by the trailer).
Gwen sat alone in her and Arthur's chambers. Her mind was still recovering from Morgana's mental attack, every last shred of her beliefs and sanity were stripped down and replaced by Morgana's hatred and insanity. All Gwen could think about was what happened over the past few weeks and she recalled the tower, the mandrakes, the visions and what it had cost for her to be free. Her hands began to shake and tears began to fall again as she replayed that same sight over and over again. That room in the tower where she had been forced to wait and watch Arthur be smite down in front of her except it hadn't been Arthur who had charged into the room.
It had been Elyan.
The sword hovered in mid-air in front of Elyan who raised his own. She screamed at him to run, to save himself. The sword had been enchanted to fight to the death to save her, he never stood a chance but he fought anyway. The sword eventually pierced him just below his shoulder and he managed to send it out the window and shut it before collapsing. By then it was too late.
"Father would have been proud of you." Those were the last words she'd ever said to him as his breath weakened and his eyes shut as Arthur , Merlin and the knights ran into the room, moments too late.
Gwen thought about Elyan. She thought about how they were younger and would play together, how after their mother died Elyan had gone off the rails slightly and she had to reign him in and be both a sister and a mother to him; ensuring he was looked after and kept out of trouble. She thought about how they had lost one another before and how they had found each other again both when Elyan left and she was exiled. She thought about the night he had argued with his father and how not so long ago they had stood at their father's grave, agreeing about how proud Tom would be of what they had done with their lives. The only small comfort was the idea of her family being reunited, her mother, father and now Elyan together and possibly watching down on her. but it wasn't much of a comfort.
There were other little details about Elyan which Gwen thought about. When they were little Elyan used to pretend to hate her ideas for their games but always found a way to incorporate them. He always gave her the nicer or bigger half of any food they shared. He never complained if she'd had a bad dream and either hit him or woke him up to ensure the monsters had gone away. When they got older any boy who even looked at her soon found themselves being warned that if they even considered hurting Gwen, Elyan would make them pay and they had a bribery/blackmail system wherein she covered for him when he got into trouble in exchange for him tidying the house and doing her chores while she was at work. Even as adults Elyan was the only one who got away with calling her 'Gwennie' and would still occasionally ruffle up her hair usually before a meeting or feast. All these things had been done due to the fact that as her brother, he could simply do those things.
'Had' and 'was', as she thought about the past tense of her thoughts, Gwen's sadness gave way to rage. She had lost the last true member of her family, her brother, her flesh and blood but instead of mourning, she had been trying to kill Arthur as Morgana's little puppet following the same deranged ideas and justifications Morgana followed. How Morgana managed to create these new sick and twisted games used to be beyond her; now Gwen understood. Morgana's mind was lost along with any sense of reason or rationale.
Still that rage kept boiling up inside Gwen; if Morgana hadn't kidnapped her or enchanted that sword, Elyan would not have died. If she hadn't been under that enchantment she would have been able to mourn her brother, not try and have her husband go and keep him company in death. Even as she stood at the riverbank, watching the boat carrying her brother's body burn all Gwen could think about was how it should have been Arthur in his stead. All this death and sorrow and pain and destruction… how many lives must be lost in Morgana's desire for a few tacky lumps of metal? Time and again Gwen told herself that she had to be stronger, she had to fight Morgana in any way she could and yet every time she had failed. That day she escaped Helios she had fallen and Morgana turned her into a doe. During that battle Morgana had disarmed her. When she was held hostage, Gwen should have stayed in that room; the room of screams and mandrakes and apparitions but she had given in and let Morgana win.
Not anymore.
Gwen got out of bed and looked out the window. She didn't know where Morgana was and the way she was feeling, that was a very good thing. So many innocent people had died because of Morgana and now Elyan's name was added to that list. Gwen stared out at the inky black sky and frowned as she thought about Elyan's dead body in her arms and all Morgana had done to them, to all of them. This was going to end.
"You've gone too far this time Morgana and this time you will pay. I swear Morgana, I will kill you for what you've done." Gwen vowed into the night.