Name: Mephistophes "Mephis"
Appearance: Described similar looking to the devil and some are called the devil's henchmen, the Mephis are actually humanoid looking, taking on different human guises to blend into society, but when collecting 'Souls' they are more inhuman, large jaws and completely covered in red-black spikes, no tail but they usually walk around in a black blazer and red shirt and tie accompanied by black pants and black shoes. They are able to live until 100 years old before they are either killed, caught out to be killed or die. That is when they become ineffective and 'lazy' in such a way that they cannot function correctly.
Attitude: Many of them are rather fierce, not really interacting or interfering with humans. However, there are some cases of them being excluded from the race and they are sent to Earth to be punished and take human form only. They hold a lot of power and some of them are born leaders, many of them are criminals themselves.
Technology: They are at the just further advanced in stages of Earth and their technology but they run on human souls, thus barely any technology is needed as they can easily teleport from one place to another. They have no real sense of development on their planet, as they see no real need to, as they only serve their leader. (A chosen Memphis each 100 years.) Many of them float throughout space, landing on odd planets and seeing how they function and whether the inhabitants will be any use to their power source or not, then they would move on and continue the process until they have gathered enough for a short three weeks before the process starts all over again.
Backstory:
Their planet is unknown, but they've been there for a rather long time, almost the same time that the sun had existed and they've always worshipped a higher power, such as their chosen leader. It had developed into a way of living, preying on the humans that had 'contaminated' souls (ones who'd committed crimes) and taking them from the body. Many other aliens that were around this time took action against them, many starting a war. They fought, winning with many causalities. Many of them were sent to Earth due to cowardness in the battlefield, they were not born fighters but had strategies that seemed to be rather advanced. Many were strike and retreat, but with a difference. Although they themselves are criminals, they are really doing aliens and humans a favor, similar to modern vigilantes. The only reason they can survive is that they don't stay in one place for a long time, moving from one planet to another until settling into a mid-temporary planet to reproduce.
'Disposed of' is the way of exiling them in a way, but more harsh, wiping records of the mephis's existence and only a few files are kept surrounding them. They also don't accept any form of 'going against the system' sort of thing and what Sebastian, did was go against the system. By speaking out about their corrupt ways, earned him a free trip to Earth.
They haven't had many mentions in history but they were there, in many wars and bloodbaths, they were around for that. That is how many associate them with the devil as it was always bad luck if a human had laid eyes on one of them, something bad was bound to happen. Their home planet, the original one had been destroyed, leaving many of them having to relocate and adjust into different societies and customs, that is one of their major strengths. You will find many that are different shape, size, eye colour and speak different dialects, some of the remaining ones had clumped together, creating a hive minded version of their race. This was a problem, as they would have large amounts of Mephis invading countries and making a big show of themselves in recent history, they wanted to stay hidden and simply not interfere.
Present: They continue with the tradition of picking up contaminated souls. Mephis are integrating themselves slowly into the Earth communities, not many want to join and their goal is to try and find other methods of a food and power source. Many want to find a planet they can properly call home and to reproduce, to creat more of their kind. They had over 11 billion of their species, and right now, due to various conflicts, only 200 remain.