This article is rated S for Spoilers.
Some information I would've put in secrets is publicly available for Summer Camp.
Orcs are brutish beings with piggish faces and prominent protruding lower canines that resemble tusks. They are hostile to all humanoids and are known to raid villages. They live an almost nomadic lifestyle, moving to other places when they've pillaged the villages near there current location.
Evolution
The
Elves, even when they were still mostly human, were a proud group. They could not stand imperfections, so they ostracized those with birth defects. However, not all had the stomach to abandon their children. As time went on, a separate community started to form where the exiled could find a safe haven.
As those abandoned harbored great resentment towards the elves, conflicts were inevitable. The elves decided to retaliate and they were forced to move further away. For a while, a smuggling ring was operational to secretly bring forsaken children to the new location. But it became harder and harder when babies were killed to prevent them from becoming potential enemies.
With a hatred for the elves in their hearts, the unlucky started to live a nomadic life. Finding other humanoid people, they were met with xenophobia and were not welcomed into their midst. Their culture was greatly influenced by these events, becoming increasingly brutal and dark. This was further exacerbated when they got the respect from ettins, ogres and trolls for their ferocious nature. These ties soon become more, as their blood mixed and the once half-elf-like people become what is now known as orcs.
Religion
Orcs believe in Gruumsh as their creator. They have a tale about how the Gods divided the world, but left no room for the orcs. Whenever they would meet other races, they were met with scorn and often attacked on sight. Gruumsh thus ordered the orcs to lay waste to those that have laid claim to the land.
Such was the role of the orcs, Gruumsh proclaimed, to take and destroy all that the other races would deny them.— Monster Manual, p. 244
It is told that Gruumsh's fury laid waste to the moutains, forests and fields. However, the elven god Corellon Larethian defended the forest and a battle ensued. Corellon got the better of Gruumsh, resulting in his retreat. This story instills a great hatred towards the elves. Orcs have taken particular pride and joy in slaughtering elves, to reclaim Gruumsh lost honor.
Characteristics
Orcs are brutisch creatures, believed to have no conscience. They just slaughter and kill with extreme prejudice, fueled by their beliefs that the entire world has wronged them and that it is Gruumsh divine command to do so.
But hatred is taught and there are those that have rejected their savage ways. They've started to build a more permanent settlement, with hopes of living a more peaceful life, proving that orcs aren't evil by nature necessarily.
Society
Because of their nomadic nature, orcs don't generally spend a lot of time settling down. They live in wooden structures, with lots of hides to protect them from the elements.
The orcs are scattered across the continent and no one really knows how many there are. It happens from time to time that a scavenging party finds a new place that they think is great for settling. They then quickly grow in numbers without the other tribes knowing about it. Consequence is that most orcs are convinced they're always at the brink of extinction, so they need to procreate to ensure their survival. Meanwhile, their enemies see them as an unstoppable plague.
Relationships
Orcs are indiscriminate with whom they procreate. While the chieftain is known to have some wives all to himself, the rabble don't form any intimate relationships. This also protects them from having to mourn losing a loved on, since death is just part of the neverending cycle for orcs.
Orcs have relationships with different races. The have close ties to ettin, ogres and trolls, which regularly are among their ranks and live within their camps. They are also known to rape humanoid races, with a noteworthy exception being any elves.
Governance
It is hard to define orc tribes using a single system. In most cases, the most brutal and successful orc is the undeniable ruler of the tribe. They are known to hoard wealth and wives for themselves, making it lucrative to be at the top. So in a sense, it's a combination of a militocracy and kleptocracy. These leaders have to keep proving they deserve to be at the top or they will be dethroned for a new leader to ascend.
Some tribes try to find a more stable governing system, but if a successor is a disappointment to the tribe, they'll be quickly replaced. Some tribes will temporarily be a patriarchy, where the male elder is the ruler. It is not unheard of for tribes to be a matriarchy, as long as the matriarch has the cruelty needed to compete with men.
External Politics
Orcs are widely known for their aggressive raids, believed to be fueled by a lust for slaughter. They're basically in a perpatual war with the humanoid species for as long as people can remember. There's little sense in attempting diplomacy with a vicious beast, and orcs are just that, although a little bit more organized. Orcs are attacked on sight and the inverse is true as well. Orcs will take every opportunity to slay, pillage or rape any humanoids they come across. In most cases, they leave a burning pile of rubble in their wake.
