My friend and I have an idea that I find to be good and unique. Basically, his idea is this:
Everybody dies eventually. Some just die in more gruesome, bloody or downright horrific manners. Some of these people become Reapers. When they are chosen by Lou, they are brought to a pure white, empty room.
(this is the old idea)
After being told they are now Reapers, Lou disappears and a number of white stone slabs raise from the ground. Each one has a picture of a different type of weapon and the name of the broadgroup. Upon choosing their style, they are given choices of different weapons in that group. They choose their weapon and are able to customize its appearance. They are also given a Vessel, a small object, usually the last item they were holding. The Vessels can be anything that can hold objects or liquids, such as a bottle, a clip for a gun, a battery pack, etc. At the opening of the Vessel now sits a skull. By pressing on the forehead, the mouth opens to swallow the soul. They are then ranked on how well they do their first mission. They can save Rank Points and use them to buy upgrades for their weapon, Vessel or Cloak. The Cloaks are items they use to switch from spirit form to Reaper form.
After being told they are now Reapers, Lou pulls their spiritual weapon from their heart. Instead of becoming a spirit, they retain their physical body. The Vessels are the same as above. Everyone works up the list from the lowest ranking Reapers, which are now put into teams. The Rank Points work the same. The Cloaks allow them to do all the Reaper powers.