[quote=@pokemonfan0438]
since when is racism supposed to be a natural thing lol
[/quote]
I was actually curious about this too, since I've never heard of Dwarves and Half-Orcs being opposed to each other in 5e, though the PHB makes it clear from the onset that Half-Orc discrimination is commonplace since they are typically associated with Orcs and have some of their predispositions. (explicitly stating that they "tend to be short-tempered" along with some interesting stuff about how they "feel emotions powerfully")

Orcs themselves are chaotic evil. D&D Lore (Page 123 of the PhB) states that evil dieties (Gruumsh in this case, the chaotic-evil creator of Orcs) will make creatures with inborn tendencies matching those of their creator, and that even half-orcs feel "the lingering pull of the orc god's influence." So it's not really a big mystery [i]why[/i] there's prejudice, but why it's Dwarves in particular.

[hider=Full Excerpt from PHB p.123 on alignment]
[b]Alignment in the Multiverse[/b]
For many thinking creatures, alignment is a moral choice. Humans, dwarves, elves, and other humanoid races can choose whether to follow the paths of good or evil, law or chaos. According to myth, the good-aligned gods who created these races gave them free will to choose their moral paths, knowing that good without free will is slavery.

The evil deities who created other races, though, made those races to serve them. Those races have strong inborn tendencies that match the nature of their gods. Most orcs share the violent, savage nature of the orc gods, and are thus inclined toward evil. Even if an orc chooses a good alignment, it struggles against its innate tendencies for its entire life. (Even half-orcs feel the lingering pull of the orc god's influence.)

Alignment is an essential part of the nature of celestials and fiends. A devil does not choose to be lawful evil, and it doesn't tend toward lawful evil, but rather it is lawful evil in its essence. If it somehow ceased to be lawful evil, it would cease to be a devil.
[/hider]
Dwarves are already characterized as "distrustful" and "slow to forget wrongs they have suffered", so the many paragraphs of how Orcs pillage and slaughter from the monster manual aren't necessary to put 2 and 2 together, but was there a specific event that caused it?

The best I could find in official 5e material was an excerpt from the monster manual referencing "King Obould Many-Arrows", which took up residence in a mountain range called "The Spine of the World" and attacked nearby dwarven, elven and human settlements. After looking into it a bit more, apparently they settled in "Citadel Felbarr", which was a Dwarven Citadel before the Orcs attacked it, renaming it "The Citadel of Many Arrows" until the Orcs were later defeated and the Citadel reclaimed.

Heavy Metal is, as I understand it, more familiar with older editions of D&D, so there might be more about it in older editions. Carrying over legacy lore at the DM's whim is nothing new.

I was more irked by the seemingly arbitrary restrictions to word choice, and I maintain my opinion that, where they're accurate, they shouldn't be restricted, but I also understand wanting to get away from the negativity seen so often on social media and other places. If someone joined a game I was running and wanted to offhandedly mention a band of Druids wild shaped into foxes running disinformation campaigns to trick people into avoiding healers when they're afflicted with poison for financial gain, I wouldn't like it either, even though I fucking hate the real-life equivalent. I don't want to dwell on it in a D&D game; it doesn't matter if my players are in agreement of the real life matter or not. I may have made a smaller deal about it, but I'd ask them to drop it going forward.

I think what I edited it to arguably calls more attention to the fact that it's racially motivated, since a hate crime is a verb that can be mentioned casually rather than spelling it out. (i.e. "ATTACK THEIR HEALER BASED ON HIS RACE") I was just trying to say my character interprets the situation as beyond practical resolution through amiable conversation so he'd have a excuse to prepare for combat before it actually started.

Fantasy racism need not correlate to real racism and I don't really care where Heavy Metal's perception on what reminds him of current events lies so long as it doesn't get in the way of the writing and characterization. Despite invoking the Streisand effect and his rude response, jumping to a soft ad hominem by implying he's, in your own words, a "2010s /pol/ anti-sjw" based on his attempts to keep up his own immersion is disingenuous.