#siiiiiiiiigh silly sleepy apples yappin' way earlier in the morning than she should be again what else is new

[applestorms]

two ways that i think you could potentially read this panel (and o!ciel's reaction to his brother coming back more generally):

OPTION 1: o!ciel has given in, fallen for the allure of the power that holding the title of Earl Ciel Phantomhive has granted him. he has gone on w/ this revenge plot (revenge for himself, as he specifically states during EWA, not his dead family) for long enough that he has essentially given up on all of his old familial attachments.

nobody matters except Him now, and maybe the people he can use to get what he wants (sebastian most notably, but perhaps also the other servants, so long as they stay useful). it is the Title and Power and Status that he holds dearly here and that he wants to retrieve, everything associated with the Earl name and his job as the queen's watchdog that he has so painstakingly worked at over the last three years. he wants his land and his life back, and he will do anything and shove anyone down to get that power back.

OPTION 2: o!ciel does not see the undertaker-revived bizarre doll r!ciel as his real brother. rather, o!ciel sees undertaker's revived r!ciel as a fake-- an imposter, if you will. amogus.mp3. and not only that, but this particular ciel is an even worse copy than he is in his eyes, less deserving of the name Earl Ciel Phantomhive than o!ciel himself, who at least can truthfully claim his right as the original ciel's twin brother. he doesn’t just want everything associated with the name, but the name Itself in the case.

when undertaker's true identity as a shinigami and plot regarding the bizarre dolls is first revealed on the campania, o!ciel is visibly disgusted by the very concept:

similarly, earlier (in the timeline) when he is first making his deal with sebastian, one of the first things he catches sebastian off guard about is seeing straight through his lie about the possibility of bringing his brother back from the dead (ft. one of the best seb faces ever):

note o!ciel's wording here in particular: "In other words, it's impossible to bring the dead back to life. You are incapable of turning back time."

even at what is essentially his absolute lowest point in the entire series, when minutes earlier his despair and onslaught of emotion managed to summon a literal fucking demon, o!ciel still has absolutely no doubts that his brother is Dead and going to stay that way. his first act in tethering sebastian here is motivated by this clarity of mind-- in fact, this is one of the ways in which o!ciel and sebastian are completely in agreement imo, and why undertaker himself works so well as the ultimate antagonist of the series, since he is essentially perverting this natural order that both seb & o!ciel are so attached to, one where death is Final and Absolute and Complete.

in other words: just the same as his twin, o!ciel Will Not settle for any fake brothers. a replacement, particularly one created and raised and under such horrendous circumstances, is entirely unacceptable.

honestly, i think there's at least a little bit of both of these options in o!ciel's claim to the Earl Ciel Phantomhive name up in that first panel at the top of this post. but personally, i definitely lean towards the second one holding more weight-- o!ciel is not someone who we see showing all that much respect or care for all the Earl rich boy bullshit, other than through the connections and power it grants him in the process of enacting his revenge. hell, in his whole angry spiel before this, he even explicitly calls the job itself "bothersome":

certainly, he calls r!ciel, "the real one," here. but more notably, i think his internal logic is revealed more by this other line-- "No one suspected me as fake! For three whole years!"

o!ciel might not be the "real" earl ciel phantomhive, the one born to the name and the title, but he is certainly a better, more deserving fake than this bitch that has had the audacity to drag himself out of the grave three years after his destined end. thus it is o!ciel alone who deserves this name and title and everything associated with it-- nobody else.