Grell and Undertaker are extremely popular and always included in merch and other things along with the main characters Ciel and Sebastian, especially Grell who is always included in the "main trio" despite being a side character. Do you think there will be backstory chapters for them? The servants had their backstories revealed and they aren't very popular...
I think the chance of them getting a backstory is 50/50 for a few reasons I will illustrate below.
Undertaker is the third most popular character in the series, and in Japan, he enjoys this rank mainly because he is 1. a very powerful and handsome character (sadly, one cannot deny that many in this fandom are indeed mostly drawn by the eye-candy), and 2. a very mysterious character.
Of course, Undertaker is - until proven otherwise - basically the main antagonist of the series now, and the marketing of the manga might really benefit from having a backstory on him. Many readers are very curious about who he really is, how he came to be a reaper, and why he is so obsessed with the Phantomhive family. For the shippers among us it might be satisfying to see some type of romance being confirmed between him and Claudia Phantomhive. For the non-shippers, it would be gratifying see a narrative that focuses on whether he had any influence on Claudia Phantomhive as the Queen’s Watchdog herself (much like Sebastian has on O!Ciel).
In short, giving a backstory to Undertaker would serve to quench some curiousities in fans, and if not, then at least some thirst by presenting more panel-time.
As I said above, part of the main reason why Undertaker is so popular (in Japan at least) is because he is mysterious. The core of mysterious characters is that there is a lot we don’t know about them, without the lack of information distracting from the appeal. (A character whose lack of information DOES distract from the appeal is not ‘mysterious’; that’s just ‘vague’ or ‘underdeveloped. Yes, it’s a fine line, but these do sadly get conflated a lot…)
There is an enormous risk to revealing too much about a character whose main appeal is the mystery. Once the disclosed canon backstory does not appeal to the fans of the character, this character’s popularity really might suffer. Of course, there has been a lot of theories in the fandom, and Yana could - if she had the time/wanted to - do research on what is the most welcome theory.
Yana has two things she could do then:
Give the readers the most accepted/popular fan-theory, either because the fans guessed right and continue her intended route for Undertaker, or start writing the story towards this route. Some readers might be happy that they were “right”, while other readers might be upset because the product would be “predictable”.
Give the readers a ‘surprise’, but risk the backstory not being well received, or worse, rejected.
Nowadays consumers of media really have this urge to ‘be as smart, or smarter than the media they consume’. In the internet age, it is impossible to stop the overexposure of fan predictions. In this constant ping-pong of information, many brilliant minds can come together and it is inevitable that at some point - IF the story is well written that is - readers will be able to find the solution to the puzzle.
Let us just consider the hot mess that is HBO’s Game of Thrones…
“I struggle with this because I do want to surprise my readers, [……] Some readers in internet boards got the clues. Do I change it? No, I can’t, as I had planted them and it would be a mess. I’ve been planting all these clues that the butler did it, then you’re halfway through a series and suddenly thousands of people have figured out that the butler did it, and then you say the chambermaid did it? No, you can’t do that.” - Game Of Thrones author George R. R. Martin.
With the 2CT having went on for approximately a decade, Yana must be painfully aware of her cornered position as a writer in revealing the truth behind the Phantomhive twins. I personally think Yana might think twice about whether she is going to give readers anything about the Undertaker.
We have evidence from the past that Yana does not mind keeping the mystery in her stories.
“However, I’ll probably never state clearly what Sebastian’s true nature is […]” Cited from the translation by @akumadeenglish .
If she is not going to reveal too much about the titular main character of ‘Kuroshitsuji’, it is not inconceivable either that she won’t for Undertaker.
The real question we (us fans as well as Yana) should be asking is; “do the readers really ‘need’ a backstory, or do they just ‘want’ it? If we do get one, then at what cost?”
Perhaps the Pandora’s box might better be left unopened.
Likewise addressed in the same post before, Grell is popular because she is: A super powerful reaper who transcends traditional gender boundaries, and is funny.
There is considerably less risk to revealing Grell’s backstory. Her backstory is not necessarily what the fandom is thirsting for, but the question really would be: “why not?”
Finny got a mini backstory, Meyrin seems to be getting one, so it would not be a stretch if Grell got one of her own too. The only real requirement her backstory would need is a timing in the current plot that would allow for one, without it distracting too much from the main plot.
On the other hand, Kuroshitsuji SEEEMSS to possibly, maybe, perhaps, be heading towards the end. Even though I am sure Yana’s earned enough money to live the rest of her life without worries, what is she going to do next?
It is VERY hard for successful manga artists to finish the successful franchise, start a new one, and to have that new story not be known as “by the same makers as XXX!” (See Death Note… See Fullmetal Alchemist.)
Also, marketing wise, Kuroshitsuji is ‘a’ or even ‘the’ support pillar of G-Fantasy. I am not sure how well G-Fantasy would do without Kuroshitsuji. Most mangaka have no say in when they can terminate their own story; they usually get the instruction to just go on and on, until the content is not ‘milkable’ anymore, and then get terminated by force. That is the exact reason why many mangas having a VERY dragged out and sloppy ending.
If Yana also has no say in whether she terminates the story or not, she might really use backstories, spin-offs, etc. to stretch out the material. Of course the main reason why Kuroshitsuji’s pacing feels very slow now is because 1. the chapters are very short for a monthly published manga, 2. the art is VERY detailed and it takes Yana double the time to draw X number of pages. But most importantly 3. probably because G-Fantasy wants her to drag it.
Unlike Undertaker, the fandom (Japanese or otherwise) seems to be less busy speculating about Grell’s backstory. It is possible that it’s simply because Grell’s character just does not beg for as many backstory-speculations, as her main thing is not the mystery. (And also, probably because most people in the non-Japanese fandom have been too preoccupied with arguing what her gender is…)
Just like with Undertaker, disclosing a backstory might risk it not being well received. Most Grell-fans seem plenty satisfied with just knowing what we do already. As there is less thirst for Grell’s backstory, Yana does not have to risk her popularity.
Most fans would not MIND or are curious for a backstory, but the same question as above: “do we really need it?” is likewise the question here.
Yana might give us a backstory for Undertaker, but it really would be a gamble on her side. As for Grell; she might, she might not. The risks are lower, but she does not need to take the risk.
Considering the nature of media consumption culture, perhaps Yana may better opt for ‘better safe than sorry’.
