The plight of Lady Pole: magically bound to attend the Gentleman's balls every night, unable to tell anyone about her suffering, and treated like a mad woman during her daylight hours.
Jonathan Strange's reaction when he removes his sanity and forgets who he is.
Strange: "He had a wife, you know. Arabella Woodhope. The most charming girl in all the world. But dead. Dead, dead, dead. In fact, now that I come to think of it, was I not in love with her myself? I think I must have been. She had the sweetest way of saying my name and smiling at the same time, and every time she did so, my heart turned over. You know, it is really very- ridiculous, but I cannot actually remember what my name is. Laurence? Arthur? Frank? I wish Arabella were here. She would know. And she would tell me too! She is not one of those women who tease one and insist upon making a game of everything long after it has ceased to be amusing. By God, I wish she were here! There is an ache here." He taps his heart "And something hot and hard inside here." He taps his forehead.
There's an especially bittersweet note to it, which is that this particular persona of madness disgusted Strange once he was sane again- he compares himself to Lascelles or Drawlight and hates how shallow and foppish he acted. Even his vainest, shallowest self still misses Arabella with all his heart. Loving her is still a part of him even when everything else (his magic, his inquisitiveness, even his name) is gone.
Arabella's false death.
The description of the meal after Waterloo, where the officers wait for their dead friends to return from battle.
Stephen Black picturing his mother dying alone in childbirth on a slaveship, surrounded by strangers who didn't speak her language. The mini-series makes it worse because the Gentleman actually shows Stephen a vision of it happening. It is heartbreaking.
Norrell's depressed reaction to learning Strange is leaving his apprenticeship, where he even bargains with access to his precious books to keep Strange by his side, against all of Lascelle's plans. Norrell never before had a friend and an equal to share the most important part of his life with, and he's realised that he has driven away the one man he appreciated most.
In the BBC series:
The death of Jeremy Johns, and Strange's wretched attempts to save him and the books.
Lady Pole is chained up in the attic as Norrell tells her, however apologetically, that in order to return magic to England and win the war against the French, he's going to sacrifice her for the greater good and leave her enslaved to the will of the gentleman. And then reveals that she's got 75 more years of this to look forward to. Hardly surprising she starts biting and screaming in absolute despair.
The Stranges' wretched reaction when Jonathan is conscripted back into the war against Napoleon, having just promised to retire back home to Shropshire and work on their marriage.
Strange's denial of Arabella's death. He even attempts black magic to bring her back.
Jonathan eagerly preparing for what he thinks will be Arabella's resurrection, even arranging some flowers and buying a dress for her - and his utter despair when the gentleman refuses to resurrect her. In the end he begs the gentleman to give her back, ironically not knowing he is her captor.
I have been working for it all this time. I have sacrificed a great many things. I did it all in the fervent hope that you would bring my wife back to me... I've pictured what it would be like to see her again, sir. The smell of her, the image of her face in my mind, all of these things that I'm beginning to not quite remember. And everyday that she went further from me, I consoled myself with the thought that she will be close to me again. Please.
Stephen's reaction to Vinculus' hanging, believing that now there is no hope for him escaping the gentleman.
Norrell's tired, sad reaction to Strange's mocking laughter at his attempts at combat magic - which amounts to a minor indoor rainstorm, which comes off as utterly pathetic by comparison to the more mercurial and imaginative Strange, who despite being at death's door, is by far the more accomplished combatant - which as one reviewer remarks, causes Norrell's entire childhood and past to unfurl before us, explaining his uptight nature, defensive pride and monomaniacal obsession with making English magic 'respectable'.
Please do not laugh. It is cruel to laugh.
Norrell protesting, clinging to, and eventually agreeing to sacrifice his volumes of magic to summon the Raven King. Any book lover will share his utter heart-break at having to give up the books he treasured for so long and loved so much.
Jonathan and Arabella saying goodbye, as in this version their chances of a reunion seem even smaller.