Hi, everybody! In this suggestion, I'll be talking about my favorite race of Middle-earth: the Orcs. This suggestion will specifically be focusing on their origins, as well as their... breeding habits.
Haven't clicked away, yet? Excellent!
Orc Creation
Tolkien never really settled on a definite origin for the Orcs. In the published Silmarillion, Orcs were originally bred from Elves captured by Melkor. However, Tolkien didn't publish the Silmarillion himself, and he had dropped the Orcs-from-Elves concept after a while. There were several other ideas he had thought of, including Orcs are animals taught to speak, Orcs are Men, Orcs wormed their way out of underground slime like maggots, or (my least favorite) Orcs are descended from fallen Maiar.
Obviously, the mod currently subscribes to the Tormented Elves theory. Personally, I'm not really satisfied with that theory being the sole and clear Orc-origin in the mod, so I'll try to muddy up the waters. Just to clarify, I'm neither suggesting different options for Orc-origins, nor am I suggesting one single origin. Rather, I'm suggesting multiple vague origins to be added all at once.
New Features
Structure
Orc Breeding-Pits:Small delvings found far underground in Mordor, the Misty Mountains, Angmar Mountains, Forodwaith Mountains, and the Fire level of Utumno. They'd be filled with waste blocks and a new block similar to quagmire (I'll happily take suggestions for a name). Inside would spawn about two Orcs of the faction, but the primary inhabitants would be Orc-women and their children. This structure would be similar to those slime sack things in the movie, but I actually have in mind Tolkien's initial origin, where they were "bred from the heats and slimes of the earth". Obviously, I've reworked it a bit to bring it in line with the other theories.
Mobs
Female Orcs: These Orc-women would only spawn in breeding-pits. They'd be clad only in rags, similar to the ones worn by Tormented Elves and Corrupted Men. When approached by a player with negative alignment, they would immediately attack, with quicker speed than their husband, dealing swift but low damage with their bare hands. They'd have the same health as their male counterparts.
Orc Children: Once again only spawning in breeding-pits, they would be small, about the size of Hobbit or Dwarven children. They would spawn with no armour, and their textures would be just like their parents; one difference is that their eyes would be screwed shut (not really any reason for that, it just adds to the creep-factor). Orc children would occasionally eat Man-flesh, and more rarely rotten flesh.
Breeding Orcs
Unlike Dwarves and Hobbits, Orcs wouldn't be bred with any sort of awesome-looking spiky Orcish Marriage Ring. Instead, the breeding process would be closer to breeding animals. Man-flesh would have to be fed to both an Orc and an Orc woman nearby, and they'd both initiate the process. I don't think heart particles are very fitting here, so there would instead be a dark, brown-green smoke effect (more ideally, a splatter effect, which has the positive downside of being grosser). Soon after, they'd spawn an Orc Child, and there'd be a cooldown before you can use both Orcs again. Breeding Orcs would add +5 alignment to the appropriate Orc faction, but subtract -2 from all Elven factions. Obviously, Utumno Orcs can't be bred by the player, and would be hostile. Occasionally, they'll breed on their own.
Achievements
Black Evil: Kill a Corrupted Man.
Vilest Deed: Breed two Orcs together.
They were like animals! Kill an Orc-woman and her child.
Conclusion
That's all there is to it. As I said above, there shouldn't be a definitive origin. To do that, I mixed all the different ideas together, and threw a few separate ideas in different places to further the confusion. Consider these waters muddied. Obviously, I omitted Orc-Maiar, since they didn't really fit anywhere in this suggestion (and who will really miss them, anyway?). EDIT: I've removed Corrupted Men, since they didn't really fit in with the rest of the suggestion (plus, doesn't make sense with the timeline).
If you have any ideas to add on, or want to complain that I grossed you out, feel free to comment!