Some little inconsistencies in the story had already happened at that point, but nothing major to the point of calling it a plot hole I would say. You see, the whole problem with the yoki-sensing element in the story, which is a major one and has been present since its very beginning is that it can potentially conflict with or constrain a lot things like 1) plot direction and/or story building; and specially 2) dialogue and interaction between characters. Constrainment would potentially happen during the creative process I imagine, if it ever did, conflict would probably be the more suitable term to describe and the end result that we see is an inconsistency as the plot or dialogue will most of the times take precedence. A bit more about that later.
Information that some characters should be aware of is often ommited or presented in the dialogues itself, sometimes to the surprise of said characters. I could present several instances when such a thing happens. You can say that the bigger the yoki-sensing capabilities of a character, the bigger is the chance that one such inconsistency can happen. Galatea for instance has arguably several of these.
We can have Galatea being
awesome in a chapter by far outranging even a very good yoki sensor in Tabitha when she felt Isley's struggle far back in the south, and picking up the aura of Dietrich on yoki suppressants nearing the city. Then later on she can be made seemingly
clueless as to Cassandra's movements from the east towards the center region, when
Tabitha and pretty much
everyone from the single digit ABs had been monitoring Cassandra for quite a time, potentially days.
These inconsistencies are either overlooked or purposedly made I think, as doing so makes dialogue between characters flow in a more natural way, specially for the average reader, whereas if much of the information was such a given, it could potentially make for a harder to read and interpret dialogue and story overall. It's also important to note that despite being a monthly manga, Yagi-sensei and his assistant(s) scheduling must be as hell brought to earth as it was for the Claymore world when he brought it the Destroyer. It is with most mangakas as we all know. Every chapter must or should accomplish something to move forward the plot and story progression, I imagine that scripting and story boarding/sketching comes first on schedule and losing precious time and/or panel space with details that most people don't notice is most probably not the best decision considering where he is standing. Besides, I'm not sure Yagi-sensei himself even cares too much for nicely wrapped up story and universe consistency to be honest, given some of his words that can relate to this subject on the few interviews of him that I'm aware of.
As mentioned earlier, it's an element that can also constrain or interfere with intended plot direction. This is the most problematic aspect, as it can be much less subtle than the previous problem and is something that story writers usually do not appreciate much as it may limit storyline possibilities. Despite the yoki-sensing element being already developed in such an all encompassing way, if it conflicts with the intended storyline the author wants to follow, it will probably be ignored in favor of where the autor, Norihiro Yagi, wants to get the story at. Most would agree that plot should take precedence over in-universe rules or elements, and in the case of Claymore it always has a chance of being overlooked, given how subtle and intangible some elements can be.
So finally lets start talking about A&B during the Destroyer arc. They were one of the big players of the large scale conflict that happened during that arc. Their initial role was to leave the Org and carry an Abyssal hunt, looking to slay Riful, the last standing of the old and classic Abyssal Ones. That in itself would lead to the progression of Miria's story thread to bring down the Organization, as Miria was not making her move while Alicia and Beth were stationary there. Then meet Riful. I personally liked A&B's clash against Riful and Dauf, it was brieft but interesting and well handled I thought.
Now the moment when the story, in my opinion, falls somewhat from its tracks and starts to not make sense with its own inner rules and also in other different ways starts when the Destroyer is fully awakened and begins to bring hell by firing volleys of parasitic hell cat rods all over the place.
The plot twist where Beth gets hit by one such rod was too forced to me, speaking strictly from a world building and universe consistency POV. I will try to present why I think this way and deliver counter-examples found within the same arc to show how rooted on plot reasons and plot driven it is, to the point it may be within plot hole territory when conflicted with several elements and events that happen in the aforementioned arc.
In order to do that, lets first talk some more about the ever so present Yoki Sensing framework or foundation that exists within the series, along with other related concepts and how they have been portrayed in the series. There can be a strong correlation of concepts within this same framework and despite all the little inconsistencies that we may find (like the one pointed above), the framework has actually been portrayed as a pretty self consistent set of thoughts and ideas, to the point where we could even predict some small developments in the story (it's been my experience a couple times). YAY, Claymore Science!!!
One concept that is deeply associated with Alicia and Beth is the soul link. I won't get into too many details about it over here, but the main principle for the formation of the soul link at that point in the series (and probably still), was the yoki-alignment. When we see it for the first time we have Rubel and Galatea introducing and talking about the essence of it in a crude way, and it is taught that it is much similar to Galatea's yoki-manipulation tricks, that are based on yoki alignment too. At some point in the series yoki-alignment between claymores is not portrayed as something to a selected skilled, but a technique that may be picked by nearly any claymores and used mostly with the purpuse of accelerating regeneration and healing, with varying degrees of proficiency. Yuma, Cynthia among several others show this trend (although Cynthia does seem to have some nice sensing skills overall upon my last re-read). It was and is natural that some claymores with very strong and acute sensing skills may develop techniques that involve yoki-alignment (think Galatea from Clare's generation; Raftela from the most recent one and you can go as far back as the first generation with the turtle AB that showed up in Pieta); and it's also fair to assume that by the other way around, the continuous exercise of yoki-alignment leads to improving sensory skills, specially the sense of minuscule, faint traces (and that may also apply to either doing or receiving the healing boost/wave).
So I went to some length to establish that there can be a strong correlation between perception and yoki-alignment (and possibly the other way around). With that said, Alicia and Beth are said to achieve perfect yoki-alignment among each other, something that Galatea said that even she couldn't do it, at least 7 years ago in the story. Perfect alignment may enable complete control of the other one's actions. If Galatea was able to reposition Dauf's attacks with her alignment, perfect alignment would enable to completely stop it at its tracks (something she might have achieved recently, as she's shown to shut the movements of some AB's for a brief period, which is pretty darn impressive btw). While Alicia and Beth have some things going for them, like sharing the flesh of the same yoma, having a more similar organism to each other thanks to being identical twins and also the rigorous training regimen that they have gone through since an early stage, their yoki-perception qualities should be justifiably extraordinary at this point. Long story short, they are an A+ in the databooks on yoki-sensing, which is pretty high and the same as Galatea.
Claymores with sharp sensing skills may show aptitude for the famous pre-emptive yoki sensing (PYS) skill, where one is able to rely on one's sensing to detect the movement or maneuver of the opponent, as yoki is or should be almost invariably the first signal to light the impending movement, even before the movement itself happens. That's why it's considered to be very powerful on capable hands. Teresa was the first to show the technique, and still has been the most proficient at it. Clare inherited the technique as well, while Galatea locked herself with no other option but to use it when she became blind (it might have been second nature even before considering her yoki manipulation technique) and at this point we have more than half a dozen characters who have displayed it to some extent too. So I finally reached the point where I can say that Beth was one such, and we can assume Alicia would also be able to pull it off with a good degree of skill as well. That is evidenced the moment a dumbfounded Dauf complains to Riful how Beth is dodging his rod attacks with closed eyes, so she can rely more on her yoki-perception for dodging and at the same time concentrate even more on the mental link to avoid the delays that Riful was looking for to slow down Alicia. Clare was also perplexed when she noticed Beth's movements, influenced by Rafaela's memories and knowledge about soul linking.
This can be found here, from pages 10 through 15.
Yet in the plot twist, Beth does get hit by one of the rods included in the first volley fired by the Destroyer. The fact that Beth was able to dodge projectiles that still went with quick speed at a much closer range should already present a strong opposing perspective on its own.
But we have more. One could say that the rods came flying with an even greater speed and strength, it seemed nearly instantaneous how they pierced Riful and Dauf, causing them enourmous and temporary irreversible damage (could explain why Riful and Dauf, Riful most notably couldn't turn back to her abyssal form after being hit, as one of the function of the rods that transform into the hell cats is to suck away life force).
Even then, we have two instances where Clare used her yoki sensing to completely avoid these rods. On close inspection, one could notice that Clare was actually even closer to the Destroyer compared to where the battle involving Beth, Alicia, Riful and Dauf initially took place. In the first instance Clare managed to direct Helen and Deneve to a safe place and avoid all dangerous colisions off-screen.
So how does that work? In the second instance, Clare was a bit spaced out just before the volley was fired, as she had just felt and started to remind how Priscilla's yoki felt like when she got nearby.
Yet she explains how she does it and how easily she can reposition herself and others to avoid being hit.
Even before, on the 1st volley, Priscilla had already shown us that with small adjustments you can completely avoid the trajectory of the rods being fired.
These projectiles might be fast, but they are huge constructs with a lot of yoki that can be detected way beforehand, even before they are actually shot.
And that's what both Beth and Alicia actually did here. Riful was all happy there 'Hey, alright! The movements have dropped!" then she realizes WTF was going to happen there. Considering that the movements of Alicia momentarily dropped when they felt the yoki build-up that would lead to that massive attack, with attention diverging from the enemy at hand, Beth's alertness should have left no room for surprises.
It wouldn't have been the first time that strong yoki-sensing would have saved a claymore's ass in a similar situation. The same phenomenon happens
here, when Clare feels the yoki build-up in Rigardo's violent nail extension attack that tears Deneve apart. PYS can be literally a life saver.
The whole scene when the 2nd volley starts being fired actually starts from page 12 of chapter 99 and goes up till page 26 of chapter 100. The duration of the shooting was quite exhagerated for dramatic reasons, as the scene marked the re-encounter of Clare and Priscilla after so many years. Either that or the Destroyer kept sending volley after volley in quick succession this time for some reason.
At this point it should be clear that considering several variables like distance from target, alertness and most importantly the excellence of the yoki-sensor involved (Beth), following the inner workings within the series such a plot twist should be just too hard to conceive. Yet it happens because when push comes to shove, plot trumps (and as discussed probably rightly so) over world building consistency.
This is one side of the coin of course, on the other hand, if Yagi-sensei couldn't allow that to happen then he wouldn't give himself the opportunity to create lots of cool things we see on the chapters that followed this plot twist; like the epic fights, intricate dialogue that followed and the artistic expression that he values a lot by drawing one of the most beautiful AB designs in the series, among other things.
Following a bit more this consistency breaking plot driven development, we can see even more elements that just show, again, how much plot driven this whole sequence of chapters was.
As Alicia corners Riful and a brief but interesting fight between them ensues, the next plot twist that happens comes when the fight is stopped by an instability in the soul link, forcing Alicia to concentrate solely on the suppression of the yoki on the other side, and consequently making us know that Beth must be fighting something incredibly powerful for her to be forced to use so much yoki to regenerate and empower her own attacks. Then we see the scene with Beth and Priscilla levelling their surroundings.
Now this whole scene and fight that ensues has at its core just a single purpose:
to portray how big, bad and powerful the main villain actually is after it's been a long time since we saw her in a more lucid state.
It couldn't be more obvious than that actually.
Double page spread zoomed in Priscilla's face with bubbles saying: "I'm really not interested... in insignificant weaklings like you...".
Really? Time to call Neil Tyson:
Nevermind how another insignificant weakling kicked her ass for most of the fight during Extra scene 3, or how a mind-crazed Dauf similarly beat her to a pulp. Priscilla's power while fighting with Beth did seem very inflated, specially when we consider that she was in a non-released state and even more so when Alicia joins in the battle.
Regardless of how sudden Priscilla killed Alicia, after this moment we see the final plot message that Yagi intended to deliver using the twins: the one about how despite the rude and alienating upbringing that the twins had, even in the most strange circumstances, the sisters always had a deep connection and care for one another that shows just how human they always were all along. That is shown with Beth crying over Alicia's death.
To assist in the delivery of this message we have Priscilla pointing how rushing to the other's aid like Alicia did and Beth sheding tears after Alicia was killed demonstrates that they still had a very human side deep within; and she also correctly asserted that therefore from the point of view of the Organization they are just failed experiments. How Priscilla came to understand so well the nature of the Org.'s approach and its process of dehumanization towards its subjects is something cryptic to me as we have a well established timeline since Priscilla awakened. It felt like one of those moments when the author is speaking through one of his character's lips, as they were some sort of oracle. Perhaps that's why Priscilla's eyes were half closed during that dialogue.
Just shows again, how plot driven this whole sequence of chapters had been.
To wrap things up, Alicia and Beth have a pretty clear role in the story considering all that's been mentioned. Disregarding all the inner consistency in the story, they are characters that are used as plot devices to set up the comeback of the series main vilain, Priscilla, while at the same time delivering a strong message of the persisting humanity that exists on a fundamental level on most of the subjects of the Organization, despite the efforts from the later to crush that humanity in order to create increasingly stronger and more controllable weapons. It's a big theme in the series and under this optic Alicia and Beth's existance in the story also seems to actually serve as a means to characterize and tell us more about the Organization than about theirselves. That could be why they are called the
black ones too and are also dressed as such.
These purposes, and probably more importantly, the message that is being conveyed, is condensed in the bodies and the mystique that surrounds identical twins and their connection with one another. These are
Alicia and Beth, the black ones.
Well, I ended up spending a lot of time here and covering much more than I initially intended. This turned out into a big ass essay of sorts, but I liked the exercise. Congrats if you managed to make all the way to here and hopefully this was an enjoyable read.
it makes me wanna cry.
