
It's been 5 years and I still can't get over that http://www.mangago.zone/read-manga/kuroshitsuji/an/manga/kuroshitsuji/v20/c105/pg-11/
I love Eric and Alan so much

From what I know, they are Grim Reaper characters from the Kuro musical "The Most Beautiful Death in the World." I've never seen it, but I know their names.
I don't know their personalities or story arcs, but (maybe spoilers??) I know Alan (the dark haired one) is cursed with something (the Thorns of Death?) that Eric (blonde one) has to help him overcome?

ok so, people please seat I'm about to start my presentation.
So spoilers of the musical are next
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Eric and Alan are original characters from the second musical. The musical start with there are several humans being found murdered and the queen asks ciel to investigate it.
At the same time, the shinigamis are freaking out because there are 900 souls that werent supposed to be there. So they ask the shinigamis Eric and Alan to investigate what is going on. We then found out that Alan is in fact sick with the Thorns of Death (which is like one of the few things that can kill shinigamis).
A lot of things happened (Ciel gets to use the pink dress again lol), but we found out that it was Eric the one killing all those humans, because there is a myth that if you gather 1000 souls, the shinigami infected can be saved. It's just a myth, but he says he is willing to try anything to save him.
Alan gets mad that Eric is doind this and makes him swear that he will never kill for him again. He accepts and both give up to being shinigamis and run away.
But Eric doesn't want to see Alan die (He calls him his "little ray of light"(TДT) ) so he continues and he says he doesnt care if Alan gets angry at him, he can't lose him.
When he has 999 souls, he starts to panic because he is one soul short, so he tries to kill Ciel.
But before killing him Alan gets in the way and Eric ends up cuting him with his death scythe. We get to see a bit of their past and then they both sung a duet and its heartbroking...the lyrics are literally about how they were born to meet eachother and how lonely they were.
Alan dies in Erics arms and he being heartbroken, asks Sebastian to kill him. Ciel orders Sebastian to end him and he kills him with Alan's death scythe.

Because their story's not apart of the main canon. At least, it was never animated, never written about, and they only ever had brief character cameos in the manga and anime.
Their story is in stage production format. Kuroshitsuji: The Most Beautiful Death in the World. Tbh, I didn't know anything about them either, only their names, and I never checked out either of the musicals.

We have seen them in the anime as backgroud characters or only shadows. And in the anime only that panel I mentioned before show anything about them.
Yana was involved in the story line and she also drew their characters https://i.pinimg.com/originals/6d/96/96/6d96967d441aea44271732376617282b.png
If anyone in interested I've the musical with eng subs in my google drive. Just dm here or on twitter @kaarenlosa and I'll give you access
wow he got called the next day after applying for a job. I want to be him