Heartwarming / Rivers of London

• Early on in Rivers of London, after the death of children, Leslie comes into Peter's room, strips to her underwear and the two of them sleep spooning after the horrible events before. It's absolutely adorable and shows just how much the two of them care for each other.
• Toby the comic-relief dog suddenly showing his devotion by fearlessly defending a helpless Peter from Molly's Horror Hunger, and Molly snapping out of her post-haemomancy fugue rather than hurt the little terrier.
• In Whispers Under Ground, when Peter is hospitalized, Leslie is sitting next to his bed when he wakes up. Nightingale also comes to visit and just barely refrains from hugging him, because that would be gay.
  • In the same book, after Nightingale and Peter exchange Christmas gifts (a watch that magic won't fry for Peter and a cell phone for Nightingale), Peter invites Nightingale over for Christmas dinner. Nightingale says he can't, unfortunately, because he needs to stay with Molly on Christmas.
• In Foxglove Summer, Nicky's mother brings the girl whom Peter and Dominic retrieved to the faeries to attempt to trade her for her own daughter. Peter then informs her that the girl she's offering to trade away is her biological daughter, who'd been swapped as an infant for the changeling she's been raising for ten years ... and Victoria still insists upon making the trade, because all genetics aside, she wants her Nicky back, i.e. the little girl she's been bringing up. Great vindication for adoptive parents, there.
• When Nightingale is coerced into captivity in the "Night Witch" comic, Molly overhears the electronic ransom demand sent to Peter. Even though she's terrified of the world outside the Folly grounds, she instantly snatches up a couple of knives from the kitchen and rushes out the front door, enraged and frantic to rescue Nightingale. She only drops the knives and slumps in despair when she realizes she has no clue where her boss or his captors are, and Peter consoles her and reassures her that he'll get Nightingale back safely.
• It's a small thing, but Peter notes in The Hanging Tree that when he explained transgender issues, both legal and otherwise, to Nightingale, Nightingale's reaction was genuine outrage - at the idea that anyone should be forced to go through all the trouble that trans people have to in order to establish their gender.
• In Lies Sleeping, Molly is reunited with another of her own kind: Foxglove, whom their respective backstories suggest Molly hasn't seen since she was a child. Their mutual muteness makes it unclear if they're friends, sisters, or even mother and daughter, but their reunion is very moving for both.
• Early in the first novel, Peter is briefly afraid that he'll be assigned to the extremely dangerous Trident undercover gang-infiltration program. An aside from the "Detective Stories" comic reveals that Trident had been interested in recruiting Peter, but his then-governor Neblett - a man who, otherwise, seems to detest Peter's inattentiveness and attitude - had told them to leave PC Grant the hell alone: he may not have thought Peter was a real "thief-taker" at heart, but he didn't have any intention of having one of his constables set upon a path that could get him killed.
• DCI Seawoll is a gruff misanthropic Northerner. But underneath the gruffness is a man who 100% trusts his out lesbian second-in-command, and is fast-tracking Somali Muslim Sahra Guleed. Even when ranting against "Falcon bullshit", he still unstintingly supports the Folly when needed. Jerk with a Heart of Gold indeed.
• In Lies Sleeping, Peter meets a faerie, Foxglove, who's enslaved by the Faceless Man. He gets her to open up to him—albeit without words, as Foxglove doesn't speak—and learns that she and a number of other fae were given to a mortal by her queen many years before. Two of those fae were separated from the others immediately, and Foxglove has never seen them since. He manages to get Foxglove to help him escape captivity and accompany him to safety by telling her that he thinks he knows where one of those missing friends might be. When Foxglove is cleared to enter the Folly, Peter's guess is proven right...
  ...Foxglove ducked around me and rushed to meet Molly. They both stopped suddenly, facing each other, centimeters apart. Molly's hand rose as if to touch Foxglove's face and hesitated. But Foxglove seized it with her own and pressed it to her cheek. Molly's face crumpled into an agonized shape and I thought I saw tears before she buried it in Foxglove's shoulder.
• The revelation, in False Value, of why Nightingale didn't destroy the Nazi experimentation files so many of his comrades had died to retrieve from Ettersberg: it's because the camp records had been hastily grabbed along with the twisted research data, and Postmartin convinced him that digging through those mixed-up documents is the only means by which the camp's unfortunate victims might yet be identified and memorialized. Guess what Thomas may spend his retirement doing?
• There's a moment in What Abigail Did That Summer when the junior apprentice brings the ghost of a Society of the Rose proto-feminist up to date on how far women's rights have come in Britain since the late practitioner's time. If ever a Folly-verse ghost went to its final rest feeling utter joy and vindication, that one did.