Deadly Blade

Shinigami aren't exactly uncommon in the world of ponies, but few can see them as they run along their tasks, unless something happens to make them visible to all. They take the souls of the recently departed and rip them from the cage that binds them to the world of the living (Cut the souls from the body). This prevents the soul from getting trapped and corrupted until it turns into another living creature that has no good intention anymore. (Think Timber Wolves)

Blade was born into the world of a Shinigami pony, instead of created like most of his kind. (Princess Luna created them to help keep the world in balance) As he grew up, the colt realized how lonely it was to walk the world and never be seen. Other ponies and critters would just walk straight through him, and even the souls that he took didn't know he existed. In order to try and ease his loneliness, he went to Princess Luna and requested that the magic that kept him hidden be dispelled. She told him of the risks it held, as Shinigami didn't look like normal ponies. The fear that he could cause was great, especially since he would show up right after somepony just died. He said that he understood, but still wanted to be seen, since being feared was better than not being there at all.

One day, when he cut a soul from its earthly ties, he released it, then was surprised to see an Alicorn fly up to it and used her magic to take it away. He watched in awe as she disappeared from his reaches, as a Shinigami is only allowed to travel so far towards the other side. He thought for sure that he wouldn't see her again, but the next time he claimed a soul, there she was again. This time, though, he kept his magic around the soul as he looked at her. They stared each other down a bit, trying to decide what to do or say next. But she spoke up first. She introduced herself, then asked what a prince was doing taking over her job.

Shini was surprised by her assumption at first, then quickly explained that he was a god of death, to a minor degree. That he was there to take the souls from the bodies and make sure they could get to the rainbow road. He saw a smile flicker across the Princess's face for a split second, then it faded again. She explained that what he just told her was that him and his kind were the ones to lead the souls to her so that she could help them cross over in peace.

Now the two of them are friends, on some level.