I joined the Death Eaters to protect my sister. She was a newly turned werewolf, and given how anti-werewolf the current government was, thought Voldemort was the better option. I knew going in that he was a mad man, and his organization a terrorist group, I did it anyway though, because there was no one else to protect her.
I rose quickly through their ranks; I was just as intelligent as Severus, and just as deadly as Bellatrix (but without the insanity problem), and more dependable than Lucius (translation: not a bloody coward). I know I did terrible, monstrous things; on my master's orders I killed, I tortured, and I destroyed, but where I could, I tried to make some things better. I was good at discreetly distracting him from some of his more insane (and sadistic) ideas, and on several occasions helped children escape the attacks. I was careful not to get caught; I did value my life after all.
There was nothing I could do about the whole Harry Potter thing though, that was too much of an obsession. In the end He was temporarily squashed, my sister was killed, and I was thrown in Azkaban. I knew that wasn't really the end, that He would be back, it would all start up again, so I endured. And sure enough, fourteen years later, the Dark Lord came and broke us out. I could have run then, there was nothing holding me there, but I had taken the mark, and would not become an oath breaker, even if I was a monster.
I went back to what my role was before, I followed orders, tried to tone down the insanity, and protect those I could. There were more now, instead of just protecting my sister and letting children get away, I found myself trying to shield a group of teenagers: the children of those Death Eaters who did not get sent to Azkaban. I kept attention off them when I could, trained them, and offered alternatives to punishing them for their parent's mistakes. Narcissa noticed that at least, and thanked me for it. There was nothing I could do to help her boy though; my lord was too angry, and Draco, in his ignorance was eager for the task.
Adrian was another thing, a distraction, and if I'm being honest with myself, a mistake. I should never have gotten involved with him, but when your lives revolve around death and war and you've spent the last decade in a literal hellhole, you long for something more enjoyable. He was someone to talk to, and have some fun with, but we kept it casual, anything else was too dangerous, and in any sane world we would not have worked as a couple anyway. We talked once about running away together, but in the end we knew it was nothing more than a fleeting fantasy.
I was there that night on the Astronomy Tower. I went to contain Bellatrix. She was a powerful weapon, but she always required a babysitter. I did my best to protect the children without anyone noticing, and focused on fighting the adults when I had to. How the headmaster of a school became the leader of the light forces I will never understand, though I couldn't help but respect the old-timer.
The following year was surreal, everything appeared to be in our favor, but I had this feeling, like everything would soon come crashing down. And I wasn't an idiot; I could tell that what the Dark Lord had set up couldn't possibly last. If their child-hero didn't save them, they would eventually be pushed into saving themselves. I would carry on to the end, but I knew that when the time came I would not surrender; I would go down with a fight and make them kill me. I would not go back to Azkaban. No matter what.
The night before the battle, I had a feeling that it was all going to end soon. I was okay with that, I was ready. I wanted someone to know though, what I had really been doing all those years, that I wasn't a complete monster. Silly as it was I wanted the name Alina Vallen to be synonymous with some word other than "killer", even if it was only for one person. So that night I put a collection of memories in a vile and hid it in a secret compartment in my robes, just in case the opportunity presented itself.
During the battle, I tried to fight only the adults, and when I came up against a student, I was always careful to use nothing worse than a stunner. It was madness, a war fought in a school, half the soldiers students. When the lull came I passed McGonagall's office on my way out, and on impulse left the vile on her desk, with a short note that said only that the phial contained important memories. I didn't know if she would view them, but I hoped. She always was my favorite teacher.
An hour later my comrades were celebrating the supposed demise of Harry Potter, but I knew it wasn't over. They thought one boy's death would end it all. They were fools. All they had done was make a martyr. I was utterly unsurprised when the fighting started up again, fiercer than before. I saw Adrian fall, but couldn't stop to mourn, I would most likely be joining him soon anyway. When I came up against McGonagall, I knew I was done. We were losing, and this was my chance to go out fighting. Her eyes hardened when she saw me, I knew I was a disappointment to her. One of her best students turned into a monster. We traded a few spells back and forth, then, out of the corner of my eye I saw him: Potter, engaging the Dark Lord. She must have seen him too, because she stopped fighting just as I did to look.
I knew then how this would play out. I whirled to face McGonagall and she brought her wand up, though mine was still down at my side. "Kill me." I told her.
"What?' she asked caught off guard.
"I won't go back to Azkaban." I explained, raising my wand. "Kill me so I don't have to do it myself."
I looked her straight in the eyes and after a moment, she nodded. As the curse flew at me I raised my wand as if to block, in case someone had been watching, but didn't block. I let it hit me, and then I knew no more.
Later that night, after viewing a bottle of memories, Professor Minerva McGonagall sat down heavily in her chair. The last moments of Alina Vallen's life playing again through her mind, when the woman had asked for death with a calm dignity. She had thought her a monster, but yet here was evidence of so much good, so many lives saved and disasters avoided, so many good intentions. But there was still all the bad, all the killing and torture and destruction. It all depended on how one looked at it, because in the end, weather someone was a monster or not was a matter of opinion, a subjective term; as was "hero".