Turns into a massive Tear Jerker by Last Stand of Dead Men.
A subtle one in Dark Days: Kenspeckle shows Valkyrie the 'mug' Clarabelle made for him, which is hideously coloured, large enough to be used as a bowl, and so uneven it can fall off a flat surface. And yet Kenspeckle uses it for mixing ingredients anyway.
In a way, Finbar recognising that Skulduggery has a new head.
Finbar: The cheekbones are higher.
In the fifth book, Tanith and Ghastly's kiss.
Val and Fletcher's little date near the end of Mortal Coil.
Valkyrie's relationship with her cousins is openly hostile at worst and distant at the very best. Yet when she sees their cousins (on their mother's side) making fun of them, she actively engages with them (something she usually tries to avoid at all costs) and treats them like they "were the two most interesting people alive."
It was quite a performance.
Later on in the book, Valkyrie is attacked by a remnant-possessed policeman. Carol and Crystal, who stumble upon the scene, don't hesitate to rush to her aid and pull him off her.
China hugging Valkyrie and thanking her for going to save Skulduggery. Even though you know she probably only wants him back for her own selfish reasons and despite what we find out later in the book, it still comes off as rather sweet.
"Don't call her child." Coming from Tanith and China.
Mr. Bliss going all Knight Templar Big Brother after Krav tried to kill China. As a family, they're... not particularly functional so it meant a great deal.
"The Last Stand of Dead Men" reveals how much China admired him and how brave she thought he was. China isn't sentimental by any stretch of the imagination but she loved her brother.
Near the end of Death Bringer: After the insanely terrifying, epic fight between Darquesse and Lord Vile, Skulduggery slowly snaps out of it, takes off the armour bit by bit and gets Valkyrie to do the same by telling her how much he enjoyed spending time with her.
Skulduggery singing "Me and Mrs Jones" as a lullaby for Valkyrie, who has had a rather bad day.
"I would." Skulduggery's response to being asked if anyone was willing to give up their lives to watch over an imprisoned Darquesse.
"You leave Ghastly alone. He's not to be harmed, you hear me? Don't be mean." There's enough of Tanith left to care about what happens to Ghastly.
Melissa loses her job at the bank. Valkyrie immediately says that the money she inherited from Gordon is for the whole family and that Alison is going to the best college money can buy.
Valkyrie's new found respect for the reflection in Kingdom of the Wicked and her determination to rescue it. It stops being heartwarming once you get to the epilogue but still...
Ghastly brings Tanith flowers when she's injured in Dark Days. Valkyrie hugs and kisses her on the cheek even though Tanith is covered in healing magic mud.
Despite the fact that Skulduggery turns out to be utterly hopeless at post rejection comforting, it was rather sweet that he tried to make Valkyrie feel better after Hansard rejects her and Fletcher gets a new girlfriend.
Skulduggery has a very sweet one in Dark Days when he admits the truth about Esryn Vanguard. His conclusion to his speech is a CMOH.
"I have done terrible things in my life, Valkyrie. Things that haunt me. Some of those things I had to do. Some... I didn't. But I did them anyway. For my sins I should have stayed on the other side of that portal, where I belonged. I should have been hunted and tortured until my bones turned to dust. But you came into hell and brought me back. I may disappoint you, but you have never disappointed me. And you never will."
Valkyrie bonding with Carol in the middle of Kingdom of the Wicked.
Stephanie's scenes with Fletcher are... oddly heartwarming. Highly dysfunctional, but sweet. Whatever she is, she genuinely cares about him. Which makes her a nice change from his previous girlfriend.
Stephanie's scenes with Alice. Again... highly dysfunctional but she adores that girl.
Skulduggery's Pet the Dog moments with the reflection.
Valkyrie and Stephanie making peace after she is separated from Darquesse. They both accept that they can share a life and family in much the same way they did before, with Stephanie living a normal life and Valkyrie living her sorcerer one. They even agree to share the bed so that neither has to sleep on the floor. Sadly, Stephanie gets killed soon after. After her parents find out about Skulduggery, Valkyrie, knowing that Stephanie would be the one person she could confide in, cries alone in her bedroom for her.
China's relationship with Valkyrie as a whole, being something like a Cool Aunt to the younger girl and stepping into the female mentor role that Tanith occupied pre-Remnant. China is, of course, China with all the moral ambiguity that comes with it, but it's quite clear that she sincerely cares for Valkyrie and gives her honest and unvarnished advice.
China and Skulduggery's conversation at the end of Last Stand of Dead Men. China, showing genuine remorse for the first time in the entire series, and making it very clear that, despite Skulduggery not returning her feelings, she still loves him. Skulduggery, a character renowned for his Unstoppable Rage, refusing to watch China die, despite what she did to his family and making it clear that he still cares about her.
Skulduggery and Valkyrie, mucking around in the desert. It's the last time either of them are truly happy in the book.
Scapegrace and Thrasher rescuing Clarabelle and then deciding to let her live with them. The first friends that she's ever had.
Hell, Scapegrace's reaction when he hears Clarabelle is in danger. He instantly demands they save her. And just before they charge in, Scapegrace is thinking of running away, but when he sees Clarabelle, he keeps going.
The Dead Men attempting to rename themselves after letting Valkyrie join. "Dead Non-Gender-Specific Persons" is rather progressive and adorable for men who are centuries old. Also, Valkyrie letting Skulduggery vote in private so he wouldn't feel pressured to let her join.
There's evidence that sorcerers historically didn't hold the same attitudes towards women as mortals did—eg Ghastly's mother was a boxer, Morwenna Crow led a war unit, China Sorrows was leader of the Diablerie, Tanith was trained to be an assassin etc— which makes sense. However, this doesn't stop it from being any less heartwarming, because the fact that they considered changing the name shows that the rest of the Dead Men consider Valkyrie to be on an equal footing with them.
And once they vote her in, they coin a new tradition of hugging a new entrant (the old one was apparently punching the newbie in the face). Even Anton Shudder, least demonstrative person imaginable, not only gets in on this but outright glomps her.
Valkyrie thinking that she still considers Skulduggery her hero after finding out about Vile. Not because he was a "good guy" but because he dragged himself back over the Moral Event Horizon.
Indeed, her sulkiness derives not from the fact that he is Lord Vile but that he didn't tell her.
Valkyrie's Anguished Declaration of Love as Skulduggery goes to shut off the accelerator. Somehow made even better by him not actually dying, and being a dick about it afterwards.
Scapegrace turns down an offer to be Zombie King for an undead city because he doesn't want to leave Clarabelle alone. It also turns out that harming Thrasher is his Berserk Button.
The complete 180 of Skulduggery's mood when he thinks there's a chance of getting Valkyrie back in Dying of the Light. He goes from barely saying a word to not shutting up and offering hugs. Likewise, as soon as she hears about it, China's delighted too.
Playing with Fire has a slightly fucked-up one, where China tells Baron Vengeous that Lord Vile was a greater Necromancer than he could ever hope to be.The true significance of this doesn't become apparent until Last Stand of Dead Men, where it's revealed China had feelings for Skulduggery - who was also Lord Vile (though it's heavily implied that until that point, she didn't actually know Skulduggery was Vile, until she saw him resort to Necromancy against the Black Cleaver).
After the initial freak out, Desmond's response to Valkyrie deciding to be Skulduggery's partner and embrace the world of magic. "I think it's wonderful."
From Series 2:
Skulduggery speaks glowingly of Valkyrie to Cadaverous Gant, expressing how headstrong and talented she was from the start, and how he always saw her as an equal. That said, he's been corrupted by one of the villains and now gleefully wants to kill her.
In a similarly dark fashion, Gant may be an irredeemable murderer, but he is legitimately saddened by Jeremiah Wallow's death and spends a lot of Resurrection grieving.
Omen might be The Un-Favourite, but he doesn't blame his brother, and admits he's every bit as great as people say. Auger meanwhile lives up to that, and considers his brother blessed for not having expectations to live up to, and repeatedly tells Omen that You Are Better Than You Think You Are, as well as constantly standing up for him against their parents (as Omen has the self-esteem of boiled cabbage).
While Valkyrie does eventually learn to stop hating herself, she holds no ill against those who hate her for the events of Devastation Day.
Peccant, an alleged Sadist Teacher, saving Omen when he falls out a window, and a few books later, covering for him against the headmistress. In a separate conversation with Valkyrie, he states that his problem with Omen is that his chronic lack of self-esteem leads to his refusal to live up to his considerable potential.
Valkyrie coming out as bisexual to her family, and Beryl initially seeming like she's going to say something bigoted... then remarking that she thinks Militsa is good for her and asking when Val is going to get married because she so rarely gets the chance to wear fancy hats these days.
It turns out Temper kept Hansel and Gretel.
"Razzia would have been proud."
Leibniz Mevolent's Affably Evil relationship with Valkyrie, profoundly odd as it is, mixes Worthy Opponent and Friendly Enemy. At every point he makes clear how much he genuinely respects her, openly admiring her powers and cunning, stating that he had to trick her to beat her, and sincerely regretting that he has to kill her because she is too dangerous to live.
He even takes her half-joking question of whether they could have been friends in another life seriously, remarking thoughtfully that he's never really been one for friends, and actually cracking up when - after she asks for a hug and he points out, amused, that he can see the knife she's holding - she asks for a hug anyway.
He also helps her stand, so she can Face Death with Dignity, and solemnly agrees to her last request to leave her face unmarked so her family can see her one more time.
Mevolent carrying Serafina Dey into the Eternity Gate at the end of Seasons of War, and gravely thanking Destrier.
While Omen chronically does not get the credit, it's nice to see that at the end, his Sebastian Tao/Plague Doctor persona is credited with persuading Darquesse to save the world (to the point where there's a new Church of Darquesse and the clergy are dressed up as Plague Doctors), and even more so that the Darquesse Society work out that it's him and keep his secret.
In the end, Darquesse saves the universe, and makes a few tweaks. One of them? She resurrects Ghastly.
