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.
Base Breaker: Briarthorn, people tend to either find him hilarious or despise him.
Complete Monster: Shadowstep, full stop. Sadistic murderer who takes pleasure not only in killing, but doing so in amusing ways and at particularly evil moments. Silvertongue employs him as his personal assassin for specifically this reason, though it's clear that sometimes Shadowstep's enjoyment of his killing gets in the way of actually killing. He is appropriately punished for this, but as Tick Tock soon learns, Death Is Cheap.
Crowning Music of Awesome: Okay, so far we've only had one small preview track released for the upcoming audioproject. But if Forza Soundfire's "The Journey Begins" is any indication, then this soundtrack is going to be EPIC!!
Draco in Leather Pants: The readers hold a lot of affection for Silvertongue and the Mean Six, despite the former being almost entirely responsible for the sorry state that the world is in as of the start of the plot and the latter being a group of antagonistic mares who have no real qualms against killing unless expressly forbidden from doing so. Despite this, more attention is payed to them being a family and less to their being murderous and evil.
Ensemble Darkhorse: Shroud. Silvertongue's secretary who mostly only showed up on the other side of an intercom. To the point where the author gave her a big farewell because of her popularity.
Foe Yay: Invoked by Tick Tock, who taunts Starlight Shadow's attempts to frighten Twilight's group into submission by a display of power, as her basically showing off in an attempt to flirt with her. Starlight Shadow never specifically denies any sort of attraction to Tick Tock, and the 'Chronomancer' title she calls her by, eschewing her real name, can be taken as a bit of a pet name for her. Shadowstep is the only other character that knows Tick Tock's name yet still calls her Chronomancer to her face, hinting that perhaps he too falls under this trope. Silvertongue is excluded, as he only refers to her title when referring to her and talking to others, and the two have never interacted personally.
Ho Yay: Despite their status as Heterosexual Life-Partners, Flathoof and Lockwood definitely have shades of this, and other ponies make jokes about it rather often.
In Chapter 12, when the party is stuck in a cramped space and Lockwood has apparently been rubbing Flathoof's flank, thinking it one of the mares in the bubble. When Flathoof tells him off, Lockwood doesn't outright show disgust, but actually compliments Flathoof on his toned flank. Rainbow doesn't miss the opportunity to call attention to it.
Rainbow Dash: "Aww, you guys are cute together."
in Chapter 27, the party gets new outfits to replace their tattered old ones. Flathoof's first outfit, chosen by Rarity, makes him look rather of a certain persuasion, and Briarthorn and Tick Tock, who are the only two at first that know what it represents in their world, relentlessly tease Flathoof about it. Tick Tock is the one that brings up the possibility of Lockwood and Flathoof being a couple first.
Incest Yay Shipping: There is an awful lot of subtext between Starlight Shadow and Silvertongue, who she knows as her adoptive father. She seeks to please him by carrying out his orders flawlessly, takes great pride in being his favorite, and emulates his way of speaking (though hers is a little off). He, in the meantime, adores her for her incredible power and loyalty to him and regularly makes point in front of the others that she is his favorite.
Curaçao and Insipid don't count, as their budding relationship is fairly out in the open.
Applejack fears that this will be assumed of why she likes Flathoof, and starts to distance herself from him. She isn't fooling anypony, and the real reason she seems to not want to talk to him is because she thought he was being dishonest about sharing a relationship with Tick Tock. Both of these thoughts are put into her head by "Rarity", who was actually Curaçao in disguise.
Jerkass Woobie: Tick Tock is a jerk, and she may have a heart of gold, but she's still rather a jerk in general. Despite this, she deals with significantly more punishment than any other single character in Twilight's party, nearly getting killed over half a dozen times on her own by now, and getting traumatized when she finds out that Shadowstep is a zombie that still wants her dead. Her relief that he can't follow her is hers alone - the readers know he can, and is.
Love to Hate: Shadowstep seems to be quite popular despite, or perhaps because he's so unrepentantly evil.
Magnificent Bastard: Silvertongue, to unbelievable levels. He's apparently been manipulating Nihila, the Goddess of Disparity, into believing he was loyal to her for hundreds of years, just so that he could destroy her when given the right opportunity. Yes, he deceived an omnipotent goddess.
Magnificent Bitch: Curacao', the Hyper Competent Sidekick to Starlight Shadownote Though Starlight can hardly be considered incompetent and the Element of Deception, is easily the most intelligent of the Mean Six. Her strategies are nearly flawless, only faltering thanks to elements she has no way of predicting. She is incredibly skilled at manipulation and can even deceive her own sisters while having the sheer ovaries to calmly maintain the disguise under threat of Mind Rape. She has a superb understanding of her sisters powers and knows how to coordinate them to best effect, even going so far as to make herself a target for Insipid's obsession to prevent the latter's greed from running amuck. She also quickly manages to see through the lies of her own father who as established above, is a fantastic Magnificent Bastard in his own right. Plus she's proven herself to be deceptivelyeffective in a fight. While her plans may not have the same... scale as Silvertongue's, she is brilliantly effective at carrying them out.
Red Velvet's techniques for frightening ponies may or may not actually be frightening to the reader. Chapter 24 so far is the pinnacle of her power, and she becomes so strong as to actually corrupt the text.
If one has a fear of insects, the Gargantuans are of course likely this for you.
Lockwood's nightmare from Chapter 22, as the whole nightmare itself is written without any indication that it's a dream, and involves Lockwood violently murdering Flathoof, Rarity, and Fluttershy before Tick Tock destroys him and he wakes up. That doesn't end it though. When he wakes up and is frantically begging to be let go to get away from them, Rainbow Dash and Applejack point out that Lockwood's eye has become warped and red, just like the zombies of the Blood Mire.