The reptilian Sil are similar to Humans in general size, though on average they are smaller. Silia average 120 – 140 cm (3’ 11” – 4’ 7”) in height, not including tail. A Sil's tail length is approximately two-thirds to three-quarters the height of the individual. They average 60 – 70 kg (130 – 154 lbs.) in weight.

Silia have dark green mottled brown skin. This provides excellent camouflage along the forest floor. Their eye color is generally yellow.

Ruthless, cunning, honorable, dangerous and loyal are all words applicable to silia. Their diet is almost entirely meat, making the breeding and slaughtering areas of their communities a sight unpalatable to most other peoples. They are prone to violence and murder. They even have ritualized killing and hunting of their own kind. However, even amongst a species which seems evil, there is strong culture and "humanity".

Silia have a proud clan structure. Their clans are not specifically related to heritage, but are as close-knit as any family. When young sil are born they are not raised by their parents. Each community has one or more Clutches where all young are cared for. Silia reach adolescent level development by 3–4 years old. On a semi-annual (2x per year) basis, generally around the equinox of the wet and dry seasons, all the younglings in the clutch which are at least 3 years old compete. Those who are found lacking are then marked for the Culling. At the annual median between the wet and dry season the Culling occurs—packs of 3–4 from that round of "graduates" hunt and kill those marked for the culling. This process forms an early, deep bond between the pack, removes the "unfit" from the population before they can breed, hones the nascent hunting skills of the "graduates," and forms the basis for their future development. After the Culling a great celebration occurs which includes the induction of each of the graduates into families. The families choose which they will raise and train in their craft and skills. Alliances usually form between the Culling packmates which cause further bonds between families.

When communities meet and cities form, they are always ruled by two chieftains. One from each of the clans present. Each chieftain has seven Salith, which are elite guards. Each chieftain has the responsibility of ensuring the other is fit for leadership. If he deems the other unfit, it is the job of the unfit chieftain's Salith to remove him from office—often with deadly force. One of them, previously selected by the now-dead chief, is then promoted to chieftain. A competition is then held to replace that Salith.

Silia cities are often a combination of above and below-ground establishments. Buildings are usually dome-shaped and made of whatever stone is found in the area. When stone is unavailable, hard, baked clay is used. These structures offer good protection and retention of heat. While silia are able to regulate their body temperature somewhat, this helps their surrounds remain comfortable at all times.

Few opulent fixtures or adornments are found outside or inside. Silia are very practical in this way. However, they have great love for metal. Their working of brass and refinement of steel is unmatched through most of Gaeana. Gems are also prized, but only for trade or adornment (usually in the form of necklaces or a specialized form of tiara that hooks around a sil's ridge). The most prized possession of the silia are their Gaeana Stones. As they spend more time within the earth than any other species, they also have the most opportunities to obtain the Stones. Most of the Gaeana Stones get traded or sold to other cities and peoples, making sil merchants very popular—both with nascent Elementalists and brigands.

Silia wear little clothing and have no concept of modesty. Other species have no chance to identify the gender of an unadorned sil as they have no external sexual markings. They have an excellent sense of smell and use that, more readily than sight, to identify the gender of other species and other silia.