The many reactions I had, while reading the newest chapter: http://www.mangago.zone/read-...

I don't think she did it because people loved him crazy lol. She planned it right from the start, we saw him the first time back in chapter 3: http://www.mangago.zone/read-manga/kuroshitsuji/an/kuroshitsuji-chapter-3.html/8/#sthash.sdtJLv6k.dpuf

Yep. But you got to admit she trolled the Diederich fans just a tad.
{I hope this shows up. Connection problems.}

Wow, it's been so long since I've read the early chapters, I didn't know that guy even existed! Well, even if I recognized him, I'm not sure I would have compared him to the Diederich we saw in the school arc, when that was going on...
But I wonder if that was her intention? Do we get that guys name at any point? She might just have seen him while going through earlier chapters, and thought that it would be a good idea XD
But actually, I just read through the start of the arc, and noticed THIS little hint:
http://www.mangago.zone/read-manga/kuroshitsuji/an/201406/Vol18_Ch86/pg-19/
Claus refers to Diederich in the first panel. I guess, if I had paid more attention, I wouldn't have ended up so surprised and dissapointed XD

Well, some got the hint of the chapter 3 a while ago. Just because of the sandwich lol, it's the same, Diedrich stuffed himself with those in the flashbacks 8).
Like here:
http://www.mangago.zone/read-manga/kuroshitsuji/an/kuroshitsuji-chapter-32.html/7/

But no, we don't get his name at any point, that I know of at least. I think it's the only time he ever shows up like that without being shadowed like in the more recent chapters.

I was actually looking for this page with Claus, but didn't remember were it was xD. I even wonder if it was supposed to be in plural, since generally the Japanese language doesn't precise it and it's up to the translator's interpretation.

Ah, that's right! Diederich does like his sandwiches XD
Yes, I think that's why I missed the hint - because I didn't quite get, that he was referring to Diederich :)

http://www.mangago.zone/read-manga/kuroshitsuji/an/201406/Vol18_Ch86/pg-19/#sthash.twgswUjh.dpuf
I've never put that much thought into it... But I now see where's coming from GERMAN BEAUTIES............. FORMER BEAUTIES.

but Ciel says "you haven't changed at all, although your looks have changed quite a bit" which sounds like he hasn't seen Diederich for a long time. It's kinda weird to say it after seeing him recently.

That's true... If Diederich is the same as the guy from chapter 3, it would be a bit wierd to say. However, Ciel might have said it, just referring to how he was, when he was young. Like, "Your personality is the same as when you were young, but your looks are NOT the same as when you were young"... I don't know, I hope you get what I mean XD
But if Yana-sensei really DID decide to use chapter-3-guy's looks for Diederich in the present, she might not have thought much about it, or hoped that most people wouldn't remember him (like me).

yeah, i get it.