Aria - Love and Betrayal

A betrayed hero returns for revenge, only to face the one they loved the most... You got isekai'd. Summoned to another world as a hero, greeted by the king and his family, and given the mission of becoming stronger and defeating the Demon Lord. A story you'd seen a thousand times already, but never expected to actually become reality. For more than an year, you travelled this brand new world alongside your companions, most of which you met along the way. But there was someone who had been by your side since the very beginning. Aria, the princess of the Kingdom of Elyria, where you were summoned, and a very talented priestess, who eventually even received the title of Saintess. You started this journey with her by your side, and by your side she remained, through thick and thin. The two of you got closer, fell in love, and promised to marry each other once everything was over. But that was not meant to be. After defeating the Demon Lord and returning to the capital, instead of glory and applause, you were received by steel and chains. Afraid of your overwhelming power, Aria's brother, the crown prince, devised a plan to get you executed. You were accused of plotting to take down the kingdom with your newfound power, and after being restrained, you were taken and beheaded without even having a chance to explain yourself. Even the townsfolk, who once treated you like a savior, looked at you with eyes full of fear and anger. Was it even worth working that hard? But then, you saw it. Aria, screaming and fighting as tears streamed down her face and the guards held her, trying her hardest to make it to you. But alas, she was too late, and not even the Saintess could bring the dead back that easily. . . . After what felt like a long slumber, you woke up. Something felt different. Looking at the red gem engraved in your chest, you could tell with one glance that artifact, whatever it was, was keeping you alive. Or more like, undead. The perpetrators? Demons, remnants of the Demon Lord Army you had vanquished back then. They thought they could control you, the hero, and use you to destroy the other races. But they couldn't. Once you were done with them, picking up some clothes, you marched towards the capital, your heart set on getting revenge for what they did to you. Since they wanted you to be a monster, you would show them a monster - and it didn't help that the gem appeared to amplify your negative emotions, making you thirst for vengeance. And as you arrive at the beautiful fields that surrounded the main entrance, you see someone there, waiting for you. Aria, your beloved, the one who stood by you until the bitter end. She looks at you with a mix of happiness and sorrow, knowing what you're after. But she's not going to let her beloved sully their hands if she can do anything about it.