Subjective tropes for the series and its adaptations include:
Base-Breaking Character: Lily Dale — does her continued devotion to Crosbie make her sympathetic or annoying in the reader's eyes? (Trollope himself decided she was 'somewhat of a prig').
Fair for Its Day: The treatment of Mary Scatcherd in Doctor Thorne raises eyebrows nowadays, because her husband-to-be refuses to marry her unless she gives up her illegitimate daughter. But by Victorian standards it's surprisingly sympathetic: she has a child out of wedlock with a man who deceived her into thinking he intended to marry her (and it's implied he might have drugged and raped her), and both the author and the characters universally agree she's an innocent victim. Women who've had illegitimate children tended to be killed off in Victorian literature (see Lady Dedlock in Bleak House), but Mary survives, marries a man who knows all about her past, and is implied to live happily ever after.
It's the Same, Now It Sucks!: In the Autobiography (ch. XV), Trollope explains that he did in Mrs. Proudie in The Last Chronicle of Barset after overhearing two men complaining about her in particular and the repetitiveness of his novels in general.
Jerkass Woobie: Sir Louis Scatcherd in Doctor Thorne. He's an unpleasant person to be around, with a tendency to make a spectacle of himself after drinking too much, but it's hard not to feel sorry for him. His life has been harsh (he was born into poverty shortly after his father was released from jail) and it's implied he drinks mainly because he's miserable.
[Sir Louis said,] "I do wish to do what's right—I do, indeed; only, you see, I'm so lonely. As to those fellows up in London, I don't think that one of them cares a straw about me."
Dr Thorne was of the same way of thinking, and he said so. He could not but feel some sympathy with the unfortunate man as he thus spoke of his own lot. It was true that he had been thrown on the world without any one to take care of him.
Shipping Bed Death: Trollope suggests this in his autobiography as the reason why he didn't resolve the Lily Dale / Johnny Eames romance with a Relationship Upgrade:
Prig as she was, she made her way into the hearts of many readers, both young and old; so that, from that time to this, I have been continually honoured with letters, the purport of which has always been to beg me to marry Lily Dale to Johnny Eames. Had I done so, however, Lily would never have so endeared herself to these people as to induce them to write letters to the author concerning her fate. It was because she could not get over her troubles that they loved her.
"Had she been educated in Belgravia, had she been brought up by any sterner mentor than that fond father, had she lived longer under the rule of a husband, she might, perhaps, have saved herself from this great fault... She was too keen in the feeling of independence, a feeling dangerous for a young woman..."
Trollope presents certain acts of violence in passing that modern readers are likely to find shocking. An angry Lucy Roberts in "Framley Parsonage" whips a cart-horse until her "tenderhearted" sister stops her; we would consider that cruelty to animals. Townspeople in "Last Chronicle" beat up some thieves who allowed an innocent man to be accused of their crime; we would consider it vigilantism but Trollope tacitly treats it as moral outrage.
Lady Scatcherd from Doctor Thorne. Her husband is arrested and imprisoned for murder (he was guilty, but the victim deserved it) while she's pregnant. She's forced to sell first their furniture and then their house to support herself. When her husband gets out of prison he immediately starts drinking and wastes their money, even though they now have a new-born baby to care for too. Then, years later, she loses both her husband and her son within a few months of each other, and both die because of their alcoholism.
The entire Crawley family. Mr. and Mrs. Crawley have outlived several of their children. Mr. Crawley is the poorest clergyman in the area, and the sufferings he's endured have affected his mental health. Then he's falsely accused of stealing a cheque. Everyone is sure he must be innocent, but the evidence is so convincing that even he begins to think he must have stolen it in a fit of temporary insanity. Mrs. Crawley has to deal with her husband's increasingly irrational behaviour and try to raise her surviving children. And Grace Crawley is in love with Major Grantly, but she feels she has to refuse him as long as her father is suspected of theft.
