For eons, the Sine have watched the galaxy burn.
They are the galaxy’s dirty secret, a myth, thought to be created by a long dead empire as living weapons; a foreboding presence at the heart of the galaxy where nothing exists but black holes, exploding stars, and radiation.
However they are also the galaxy’s silent guardians, protecting the galaxy from threats that have long been forgotten.
Everything that is built in the galaxy eventually spirals its way to the core, and so also they also protect the galaxy from itself, where every alien doomsday weapon, every experiment gone wrong, and every ill-fated last gasp from countless species eventually ends up there, which the Sine take it upon themselves to neutralize.
In time immemorial they have stepped in to both protect parts of the galaxy, and to scourge clean places they deem to be a threat. Where once their motivations were clear, they are mobilizing once again for purposes unknown.
The Sine are a species made mostly of a uniquely dense and strong crystalline structure, with semiconductive properties similar to silicon, surrounding a small core of organic material. This particular crystal is only found in very few places in the galaxy, and most within or near the galactic core where the constant high energy radiation allows for its growth.
For most Sine, the small core of organic material is heart of their crystalline bodies. This serves as an anchor point for them, where what parts of their brain and nervous system that haven’t been turned into crystal remain, for some, it’s the last bit of familiar organic feeling they have.
When Sine are born, they are mostly organic, but their engineered chemical make up means that simple exposure to the galactic core’s environment ossifies their issues and develops it into crystal. The process is incredibly painful and happens over many years. Because of the constant radiation around them, many of the young do not survive to maturity. As Sine get older, less and less of them are organic.
The process that turns them into crystal also makes them living energy weapons, for the crystal structure can store vast amounts of energy in different forms. This energy powers their life instead of chemical interactions, enabling them to exist with almost no organic sustenance. The same energy can be manipulated along with the crystal of their bodies to reshape themselves at will, often forming lenses to project energy at foes, creating armor or tools at will.
With their lives made up of energy, and their brains turned into what are essentially crystal based quantum computers, the Sine have a natural mastery over energy fields that is unrivaled. Combined with a physical form that is incredibly resilient, few forces can stand up to the Sine when they are on the warpath.
They were a somewhat nihilistic culture, and the Sine have make their presence known mainly in response to the use of weapons of astronomical destruction. The more high energy weapons used, the more likely that these weapons can tear apart the fabric of space, and one of the primary motivations of the Sine are to prevent this, and more, with their punishments as severe as the transgressions. Albeit, they often do not arrive in time to save lives.
For in a galaxy with so many unique species, it’s unlikely all of them are going to have the same level of empathy for another alien species. Weapons that seem abhorrent to use on your own kind can be wielded with impunity against others so different. This reality is not lost on the people of the galaxy, and many have benefited from the Sine’s protection, even if in the long run, it still doesn’t prevent genocide and slaughter on the smaller scale.
But the Sine are becoming more active. Shards, giant ships made of crystal, are seen as far as the galactic rim. Other events, like the Andromedan invasion has triggered massive mobilizations, especially when the Andromedan’s opening maneuvers were to use highly sophisticated anti-matter bombs to literally crack fortified planets apart.
Groups and individual Sine have started circulating among the galactic population, unheard of a few thousand years ago. Where some civilizations might see the Sine once in an age, now they can be seen active at all galactic trade hubs. Even so, they are still regarded with a mix of uncertainty, distrust, and awe.