Soul key.

The royal sisters Celestia and Luna rule over day and night. Unknown to most ponies there are also two alicorn brothers who rule, but not over day or night, but over life and death. One has the power to choose if a soul will die, being the more known of the two through foals tales he is commonly referred to as Reaper. His younger brother who is called Dafor Lifelock is the one who chooses which souls will return to the mortal realm. This is his lost story, my lost story.

Past

  "Brother, why do ponies have to die?" I asked my older brother, he looked down at me, his brown eyes showing kindness. His pitch black coat and blood red mane were very, no extremely uncommon on ponies, especially with alicorns, their coats should be bright and happy colors, our coats made ponies shudder or shiver in fear. But that was not only because of our colors, what we did was what scared them. We were the rulers of the underworld, the controllers of death. He chose who died and I chose who lived.

"If ponies didn't die the world would become overpopulated." He said, putting a wing around me. I curled up against him, even though he was my brother he was much, much older than me. I was only in my foalhood and he was already over five hundred years old. Before me he used to control both who lived and who died, and before him it was our parents. Our family tree was small, very small, there was only us and our parents. Our parents were around ever since life was created, they had to be since they controlled life and death. Me and my brother were the next generation, all of our parents powers had been passed onto us, and shortly after I was born they died.

"Couldn't we just populate another planet?" I asked him. He laughed.

"Maybe someday brother." Because I was so young my brother hadn't given me the full responsibility of my powers, for fear that I would be forever heartless because I had to let so many ponies die as a foal. He instead asked me for advice on the topic, not directly involving me while still preparing me for the day when I would have my responsibilities fully dumped on my shoulders. I soon fell asleep, drifting of into the world of dreams.

Present

  I looked out over the world and sighed deeply, there was so much sadness in the world and me and my brother were to blame for most of it. Controlling life and death was like a birthday gift that could be used against you if your parents want you to do something. I could save ponies lives, keep families together, but I also had to turn a blind eye to ones who need to die, make their families sad, take a life. It wasn't right but it wasn't wrong, it needed to be done. I turned around and walked back into the cave that led to the underworld, the realm of my brother and I. I flew into my room and looked into my mirror, my eyes were weathered, wrinkles of stress lay under them giving me the look of a wise old stallion. My blood red mane was a tangled mess making me look like a mad scientist. My horn was rounded at the end but my ears were pointed. On my flank was a cutie mark of a strand of DNA, also known as a symbol of life, it told me that I was the one that controlled who lived and who didn't, telling me I was responsible for all deaths, that I had to tear families apart. I heard hoofsteps from the other side of my door, then a soft knock. "Its time." My brother said to me, sadness in his voice, I walked over and opened my door, stepping outside I followed my brother as he found his way into the Court of Souls, where we decided who lived and who died. When a pony is going to die, their soul comes here to see if they will live or die. This place's time worked very differently than anywhere else's, even though souls have already died or lived up above, they were still here waiting to see their fate. As I took my seat the first soul walked in, he was pretty roughed up and looked like he had just been in a fight with a razor and lost. "So you were murdered, but you brought it upon yourself?" My brother asked him.

"Yes Reaper." The soul bowed his head.

"Well even if he brought it upon himself that gives nopony any right whatsoever to kill anypony, so I believe he should live." I said, looking at my brother.

"This is very true, you may live." My brother nodded to me and I used my powers and let the soul travel back to the mortal realm. The next soul came in, this one looked very cocky and seemed to act as of he owned the world. "So you died because you tried to mug somepony, but failed." My brother said, looking very pissed.

"Yeah, but come on! I need to get money too!" The soul said. My brother looked at me and I shook my head.

"Nope, have fun in the afterlife." My brother then used his powers to send the soul to the afterlife.

********

  It was peaceful as I stood outside the cave, looking at the full moon. I also gazed at the many stars that littered the sky, there were so many and they were all so far away, the thought of this always amazed me, no matter how many times I saw it I was thrilled each time. It also made me think of all the other ponies that were watching the same view, so many lives unaware that they soon may meet me and my brother in the Court of Souls. My brother always explained how our powers worked using a key and a lock.

"You see Dafor, ponies hold the key to death, they can hand it to us, meaning they die, and we decide whether to put it into the lock that opens the afterlife or not."

  I smiled at the memory, before he would explain it scientifically, but I never understood, so he took up the lock and key approach. We are the lock that fits the key of life he would always say to me. A lock to fit a key.