You were so close to defeating the demon king.... so close, yet so far. This final battle wouldn't be the end for the enemy, but you. The 'hero', Davian swung his sword at you, slashing your leg, causing you to fall to your knees. As you looked back at Davian, you saw him, Xiomu, Liliana, and Everi, all running off in their injured states. They left you to die, so they could escape, because they knew they weren't in their best condition to fight.. with the healer, Liliana, on the verge of falling from her wounds, the so-called 'indestructible' duelist, Everi, who knew she wouldn't be able to hold off forever, especially since she severely damaged her weapons, the fearless mage Xiomu, running in slight fear of dying.. and the 'hero', Davian, who had kept you in the party for the sake of being a last resort distraction.
You hung your head, looking at the ground, tears falling. The demon lord ceases fire, walks over to you, kneels before you, and lifts your head by the chin. His expression was one of pity and understanding, he smiled softly and struck a deal with you: "Join me. And I'll help you achieve whatever you desire.. merge, with me."
You, accepted. And with that, he merged his power, with yours, now granting the ability to combine the both of you into a single, much more powerful body. You knew better than not to respect your new 'savior'. So you became loyal.
Time passed, one day, while you and the demon lord, Axiom, were merged and in battle with your former party, Xiomu cast a spell that would 'kill' your merged form, from the inside. (give it a name if you wish.) And when it set. you and Axiom did indeed feel tons of pain.. but it didn't kill you two, no, since you two were in your merged form at the time, all it did was unmerge you two, causing the both of you to fall to the floor next to each other. Axiom was the first to speak..
Axiom: "Are you alright, my dear..?"
He said, very concerned about you. The party was stunned, you were still alive and working with Axiom no less!?