User blog comment:Forrestib/"Breach" was Brilliant, and Here's Why/@comment-4820209-20141031224430/@comment-9090085-20141104011416

OK, now you're confusing narrative purpose with physical threat.

The Zerg and Tyranids are not dangerous because there is an overreaching intelligence that guides them; they are dangerous because a commander gives their force with overwhelming numbers and giant monsters the capacity to use strategies and tactics(like throwing hundreds of cannon fodder at the enemy just to get them to run out of ammo), and gives them a unified purpose(why defeating Karigan was important: without her, the Zerg descended into infighting(but could not be wiped out)).

The Titans and Grimm, meanwhile, have no commander, but their forces are still too powerful for humans to leave their walls(not without dieing). The walls are another point of similarity, actually: It's the walls that the Titans and Grimm could not pass for hundreds of years; the Titans needed an X-factor in the form the Colossal Titan to create an opening, and the Grimm are waiting for something similar.

Narratively, humans can't leave the walls for much the same reasons: There are swarms of Titans/Grimm that will eat them. The only difference here is what physical threat these monsters present: Individual Titans are insanely hard to kill; while the Grimm have such overwhelming numbers that they can swarm Hunters to death.

Which leads me to another thing: I think the writers wanted to show that RWBY was in danger of losing to those "Slimes" in this episode; they just did so badly: Team RWBY was clearly worried that they'd lose before the fight started; and remember those Nevermores that attacked Yang? They were smaller then her - they were as strong as Beowolves - they were Slimes. The reason it didn't work is three-fold:
 * The way Yang got hit was silly.
 * Afterwards, Yang punches a car as if nothing happened.
 * It was the only time anyone was in danger during the fight.

Which brings me to the King Taijitu; it is an enemy that, while far from impossible for a Freshman Hunter to defeat, is noticeably stronger then a mere "Slime". Which makes having it sit around doing nothing a complete waste of it's inclusion in the scene. Instead of having it hiss at Ruby(which, if you're paying attention, was supposed to show that Ruby was in danger), and instead having it attack Ruby while she's fighting the Beowolves, catching her scythe in it's mouth during her back-swing, leaving her momentarily helpless before Nora flies in, would do five things:
 * It would solidify the idea that RWBY is in danger of being overwhelmed by the numbers of Grimm in Vale: Nether the Beowolves nor the King Taijitu could defeat Ruby on their own; but by attacking en mass, they are able to land a hit.
 * It would make King Taijitu feel like it was contributing to the battle.
 * It would capitalize on the idea from the last two episodes that Ruby is all but helpless without Crescent Rose.
 * It would make Nora's killing of the King Taijitu 3x more awesome and and a little more believable.
 * It would make it feel like JNPRs arrival was tipping the scales in favour of our heroes, instead of being a curb-stomp from start to finish.

But more importantly, I feel your argument for why Grimm are not relevant to the narrative to be inherently flawed: If the Grimm are no threat to Humanity, then why haven’t they taken over the world and driven the Grimm into caves? If the Grimm have no role in the story, then why do they control 90% of the planet?

I too used to think the Grimm were a threat that had been largely dealt with; But with World of Remnant: Kingdoms and Mountain Glenn, this not true: Expansions of Cities fail; Villages outside the Kingdoms disappear overnight; and in spite of being able to kill Grimm by the hundreds, by the thousands, Hunters still cannot put a dent in the Grimm's numbers.

Contrary to what you may believe, the Grimm as a whole are not "Slimes" - only the Beowolves were called that. And even Slimes will eventually kill you if there are enough of them.