So you wish to learn about Ether, do you? Well, it's a somewhat difficult topic to cover without knowing the three basic principles of Ether:
1. Ether is immaterial, it does not directly interact with the physical plane on its own.
2. Ether will disperse quickly without a source to sustain it. This source must have organic tissue to hold Ether without corroding due to the effects of hosting Ether.
3. Ether, unfiltered, is toxic to the host, poisoning and deteriorating them if enough builds up without being partitioned or compacted.
With these basics out of the way, we can delve into the specifics of what Ether does and why it does so.
Ether, named after the race that discovered it, the Etherite (Plural: Etherite), is a pseudo-element lacking the ability to directly interact with the physical plane. For years and years, Ether was considered to be a part of the Aether, a substance flowing through most life within creation, serving as a catalyst between soul and body. This was concluded false when the early Etherite found that Ether, while connected to living tissue and sparse amounts of Aether, could be removed from and around the body without causing any undo harm to it, whereas removing a being's Aether is tantamount to killing them if body and soul lack true cohesion before its removal. From here, the Etherite began to properly experiment with Ether, attempting to learn its properties, from which they gleaned two of the basic principles of Ether. Initially, this was all they could find on the substance and thus all extensive research was halted for a time until many Etherite began experiencing a sudden and often fatal illness of unknown origin. Very few Etherite connected this illness to Ether itself, having decided a lack of headway in research meant that there was little else to find, so by the time the majority of the Etherite reached the same conclusion, very few remained. This resulted in the Ether Scatter event, birthing the Aetherae and Netherin from the willingly dissociated Etherite. From here, the Aetherae continued the research of the now gone Etherite, discovering that Ether, after a period of gross overexposure ranging from days to years caused the substance to "taint" or severely poison the body without being divided or, oddly enough, compressed, the former of which being what prevented the Aetherae from immediately succumbing to the sickness their predecessors fell to. With this in mind, the Aetherae, before their untimely fall at the hands of an unknown organism, developed the Etheric Library System.
Etheric Libraries, thought to be the natural progression of Ether akin to how an ember can eventually become a blaze, are a fair bit simpler to explain in the grand scheme of things- using blanket statements mind you- but also where the complexities of Ether begin. As previously mentioned, once the first two properties of Ether were discovered, little research on it continued until the Aetherae discovered its third property and worked to prevent it from causing another sickness that wiped out their race. During this period, the Aetherae discovered that Ether held a highly adaptive property where, despite being unable to affect the material plane aside from its host, it reacted to outside stimulus the host had been exposed to, often in the perceived most optimal manner. For example after being exposed to fire, an Ether bearing person's Ether would take upon the property to best nullify fire on second exposure and apply it to the host, even if the fire was put out in the process. Additionally, it was discovered that Ether was tied to its host's emotional state, where a calmer host would have less drastic Etheric Reactions to outside stimulus, while a more distraught person would suffer from more drastic reactions. At first the Aetherae were baffled by this property, but, due to records from the Etherite, they soon figured that Ether was the reason for their unnaturally swift adaptation to various environments. This ability, however, was lost when the Etherite divided themselves into two different races to save themselves, thus this effect could no longer be replicated without finding and applying Ether to their sister race, the Netherin. This idea was quickly shot down for both ethical reasons and the inability to 'find' the Netherin in the first place, thus Hyper Adaptation was lost and instead replaced by Hypercompetence. This "lesser" ability would come in handy when it came to dealing with matters of Ether, as it allowed for the first Etheric Network, the interconnection of multiple individual's Ether allowing the transfer and sharing of knowledge for short periods of time, akin to the lost art of Melding, which in turn allowed for the equally swift creation of the first Etheric Library, a "compendium" of knowledge held by a group of beings having amassed various amounts of knowledge and experience over a wide array of subjects condensed down to a point where it would prevent both an information overload and the sickness caused by overexposure to Ether. With this all said and done, the Aetherae attempted to replicate the creation of the first Etheric Library and succeeded, both on a larger and smaller scale, and soon enough personal Etheric Libraries and Etheric Networks developed, signalling the beginning of a period of great diversity of the use of Ether and Etheric Libraries.
For all their worth, Etheric Libraries were essentially Ether that had been "taught" via exposure to the outside world via host then condensed and refined into a more streamlined form that could not forget things, essentially a second memory bank in the event that memory loss occurred. They allowed for the growth of the Aetherae's Hypercompetence and refinement of practices when those with differing experiences chose to share their stored knowledge with each other. Aside from this, they initially held no practical value as any knowledge taught to them, while accessible, could not be used to directly influence the world or even their host outside of its information storage(i.e. one could be taught magic without having any aptitude for magic, but one still could not use magic, regardless of knowledge or understanding, without any aptitude to begin with) and so the Aetherae worked to allow Etheric Libraries to interact with the material plane, succeeding, but only under the proper conditions:
1. The library's host must understand the knowledge without the library feeding them information.
2. The host must be able to properly exercise the knowledge if the knowledge culminates in an action and must meet the physical and mental requirements as well(i.e. having the required limb or musculature or being able to rapidly calculate distances and trajectories).
3. The host must be able to withstand the ability they choose to use, even after meeting the requirements to use the ability in the event that it backfires or causes physical transfiguration.
4. The knowledge of the skill or ability must be complete within the library in three regards: Theory, Application and Aftermath.
5. The host cannot be disrupted while attempting to use the Library as a medium, or the effect is immediately cancelled if applicable(i.e. a spell will be cancelled if in mid cast, but not if the interruption is post cast.)
Once these five conditions were met, the Aetherae could use their initial Etheric Libraries in the material plane, albeit not without difficulty depending on the situation at hand. This was deemed woefully inefficient and soon enough the first variation of the Eteric Library, the Etheric Grimoire, was born, bypassing stipulations two, three and five so long as the host and Library made physical contact. This was soon replaced by the Etheric Codex, which also could bypass condition one if the host and Library were in contact. Soon followed the Etheric Index, which bypassed all five stipulation in exchange for preventing the same ability from being used in quick succession and so on and so forth. Eventually, the Etheric Brand was created, which required manual engraving upon the host in exchange for completely stipulation free use of the Etheric Library if the host could survive the process. This too was refined and fiddled with, birthing the Ether Sigil, Ether Point and Ether gem, each of which was less taxing upon the host in exchange for a small potency decrease in abilities. These four "physical" manifestations of Ether would eventually pave the way for the Theory of Material Ether or truly physical Ether, but by the time this could be attempted, the Aetherae were long gone and the majority of their practices forgotten...
The Theory of Material Ether, simply put, was to overexpose Ether in its purest form to the outside world. This is harder than it sounds as this would require Ether to not be connected to its host, meaning one would need an extremely dense concentration or else the Ether would immediately disperse and nothing would be done. Even then, generating enough Ether to sustain this process would be a task upon itself as to generate enough Ether naturally would take years and years of allowing Ether to simply build up as opposed to partitioning or condensing it as both would change Ether to an advanced state as opposed to a pure state, which can easily result in Ether Sickness early on if one isn't careful. That being said, if these conditions are met, Ether theoretically can become a true solid or material substance. This is thought to be a substance akin to wood or metal or even pure energy in the event that a solid form is not manifested. The actual uses and effects of this are dubious at best, but assuming that the Ether in question condenses upon materializing, it would become many, many times denser than the core of a star, but not enough to create a black hole or gravitational field of its own, likely due to its innate extra-planar properties. That being said, one could theorize that Ether would take on a new property upon taking on this new form, perhaps even that of a focus or medium from which the host could draw out new abilities and properties. With that out of the way, let us delve into why Ether acts as it does.
Explaining why Ether works the way it does is rather simple: whim. One might ask how a substance becomes the source of its own whimsy, a question to which the answer is easily reached: Ether, a natural part of certain organisms, holds no physical effect while stored within them akin to Aether but when it was initially removed it took upon the property best representing the thoughts of those removing it: curiosity. How that in itself works, one would have to ask one more knowledgeable than the lowly muse writing this dissertation. In any case, this curiosity is untamed and thus directed towards everything not connected to the Ether's host- mind you it is not known where or not the Ether lacks this curiosity about its host- and so when allowed to experience outside stimulus through the host, Ether records its host's reaction, translates said reaction into an action or trait and saves said action or trait until the host's reaction changes- generally after multiple experiences with the same or similar stimulus. Partitioned and compressed Ether can further utilize this reaction by either sharing or actualizing these actions or traits so long as the prerequisites are met or appropriately bypassed. Additionally, such Ether can better record actions and reactions of the host in relation to their surroundings due to its more refined nature; a more matured form of Ether if you would. Aside from that and knowledge that is stowed away in places unknown, Ether is still rather mysterious as a substance and is worth researching, so long as caution is taken.