My memory is a little bit hazy (aka super), so can someone please help me or correct me, w...

That confused me even more xD
But if I understand your question right, yes our Ciel is the sickly one and that other Ciel that killed Agni (T^T) is the healthy one.
That's interesting! It might be possible that the our Ciel is in fact the older one but got switched cuz of being sickly. But, whatever goes down in this story, I kind of hope the healthy Ceil goes back to the land of dead, seriously I loved Agni and now his gone ┗( T﹏T )┛

Yeah that's exactly what I meant! I kinda hope it's the case, Ciel not being who we thought he would be for over 10+ years is a little bit too much for my taste, but we will see haha

And yeah, we all want that, that said he shouldn't have a soul anymore, killed Agni and there is no real way story wise for him to coexist with OCiel, so the chances for him dying are pretty good

All we can do is theorise at this point, based on the evidence in the story. But yeah, totally would be too much for me too xD Although, this soul thing for the other Ceil is confusing :( Sebastian is here cuz his supposed to be dead, his soul was the trade, and yet somehow the undertaker managed to "Bring him back"

This kind reminds me of the titanic chapter, with all those zombies running around. Maybe, the other Ciel never came back, his just a zombie that the undertaker created, but with a brain? With other Ciel's memories & personality?? Maybe, this is why he acts & feels like its him? - Me assuming xD

OMG THIS JUST MADE ME REMEMBER/REALISED!! In the Idol chapters didn't our Ciel's blood got taken???? With that crazy guy that took Elizabeth away??? OMMMGG, you know what I'm placing a ten dollar bill on the table, that it's definitely not Ciel's older bro who "came back to life" but a REPLICA OF CIEL'S OLDER BRO BASED ON UNDERTAKER'S EXPERIMENT ON DEAD BODIES + THE BLOOD INFUSION CRAP THAT HAPPENED A FEW CHAPS BEFORE!! (⊙…⊙ )

Pretty sure he is just a zombie, but if that's the case, the real question is why the Undertaker would do that?

Hmm...judging from people's theories, Undertaker is either familiar with the Phantomhives, had a lover in the family or made a promise of some sort to them. Either that or Undertaker is attached to the family similar to how Grell is infatuated with Sebastian lol xD

yeah but if he is a soulless zombie then it's basically not a phantomhive he brought back

If it's soulless though, how can it move like its thinking? The soulless zombies tend to move or act similar to the ones in the titanic chapter & yet this fake Ciel speaks, has memories & behaves like a human...probs cuz of our Ciel's blood sample..SO MANY QUESTIONS! (T^T)

impossible

that theory had already been proven false
http://www.mangago.zone/read-manga/kuroshitsuji/an/kuroshitsuji/131/pg-6/
the sickly child started showing inheriting asthma at age 5.. so i dont think they could have known about the weak constitution until the later's toddler years, So switching their position on whose elder or younger just for "show" is impossible. hehe (=・ω・=)

i don't see how that disproves anything so far

1) it's told to us from OCiel, they guy who acts like his supposedly older (and dead) brother for the whole manga until this point, so i'm not too sure if i see him as a reliable narrator..actually no i don't lol, he kept the readers in the dark and lied to them quite a lot so far
also, 2) he said their parents confused them often, they've could potentially switched their children up by accident haha
3) how much do normal people remember of their early childhood, specifically 0-5? not that much.. so a lot is possible
3) manipulation is literally not strange for this manga, it's easy to tell a child shit and make him believe it (RCiel suddenly being 'a little bit older' we don't remember our birth, so it's not like they know who popped out first, i am pretty sure you could tell a 2 y/o he's older and then later tell him he's younger, children believe in a fairy bringing them money for their teeth)
4) doctors exist (as does magic here), so OCiel still could have been tested to be weaker (they knew his mom had a condition after all) before coughing, he just knew from then on himself and it was evident for everyone around him
5) OCiel apparently was also not only weaker by body but also by personality, as the future head of the house, this also may would've been a reason to switch them up
6) again, 10 years of manga and suddenly his identity changes, let's be honest, basically everything is possible at that point, it's just the question if it's good writing and story telling by the mangaka now, i get the 'The Importance of Being Earnest' flashbacks haha (or maybe the twin isn't even real and it's an altered memory for some fucked up reason or just did in OCiels mind because he felt lonely as a child huehuehue)

there is so much at this point that doesn't make sense, and i bet if i would (re)read all it would become even more, and i am also never sure if it's clues by the mangaka or confusing translations (like the scene where OCiel runs into Tanaka before the abduction..why the hell would Tanaka tell him to stop because 'master ciel is.. this scene is much too harsh for you' lol, if someone literally just abducted RCiel, why wouldn't he try to shield OCiel from being abducted, instead of SEEING something? (and who the fuck killed the dog? there was no one in that room afterwards??) at least the flashbacks proved the rape, even though that wasn't really a secret..

all in all, i will just wait, but i am really not too sure what this story arc is good for so far, it was said multiple times that only RCiel can become the heir for multiple reason, if this is literally a big old OCiel proves himself/character growth/he can do it too i'm just disappointed because OCiel is literally only fueled by hate and revenge and the need to rise to the occasion..and there is no reason to keep that a secret from the readers at all? + why the fuck did his dad always look so strange when the twins were interacting regarding becoming an Earl lol