These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Anvilicious: When Mao is forced into a Refrain addiction, he spends two days going through severe withdrawals before he gets better, culminating in a line that reads like a drug rehab success story advertisement.
Interestingly, in the story itself, Mao gives C.C. this treatment, refusing to believe that she did anything wrong, even by giving him his Telepathy in the first place , making him completely dependent on her (though this wasn't entirely her fault, she certainly didn't help by promising to be with him forever or having sex with him at such an early age, which the work impliesfeatures ( though when C.C. admits that she really does love Mao near the end, it makes more sense), selfishly asking that he kill her, despite knowing how much she means to him and trying to manipulate him into doing so, cruelly abandoning him for refusing and almost attempting to kill him when it becomes apparent he poses a serious threat to her plan to use Lelouch to kill her instead. Pays off in the end though when C.C. finally admits that she loves him too and pledges to keep her promise to stay with him forever through the medium of C's World. Mao does slowly come to think of her as a Broken Bird though as he contemplates her Death Wish and even double-subverts this trope when he admits that though she lied to him, he doesn't care.
Fanon: While the work borrowed some novel ideas concerning its titulary character from older fics about Mao, it applies them in original ways and introduces even more new material, which has started to appear in later related stories.
Although, his treatment of Shirley is undone when Lelouch makes Shirley forget all of it afterwords. As cruel as it was, the damage wasn't permanent.
And with Nunnally, it only seems that way at first, until it's revealed it was all part of a larger planand the bomb was a fake!
C.C. herself arguably suffers one in the first chapter due to the callous way she abandons Mao, so much so that much of Mao's subsequent pining after her can make him seem like the Love Martyr.
Nightmare Fuel: Mental patients being experimented on with highly addictive drugs, Rolo's uncanny ability to effortlessly switch personalities when he's dealing with children, and some of the gruesome experiments Code-R performed on C.C., and recorded for Mao to view later.
Ron the Death Eater: As the story is told from Mao's perspective, Zero/Lelouch comes across this way, at least until Mao himself loses iteven more.
Squick: Frustrated by the lack of space on his airplane, Mao’s desperation causes him to come up with the idea to use a chainsaw to make C.C. more compact for the trip.