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.
A later episode confirms the former, though... to wit, he acknowledges that he deserves to have been shredded.
Considering when we first learn the truth about Sally's death, she mentions she always dismissed his jealousy and anger as 'passion' and such, it's hard to see how he could have been anything less than someone on the verge of outright emotional/physical abuse.
Plus his first reaction to Sally possessing the exorcist and being able to accuse Danny face-to-face for the first time is for him to try to -strangle- the exorcist to death.
Fan Preferred Couple: Aidan and Sally, if a rough search on youtube means anything. Unsurprising considering Mitchell and Annie, the UK equivalents, popularity on the original show.
Foe Yay: The conversation between Aidan and Bishop seemed pretty intense...not to mention Bishop looking in on Aidan when the other vampire is feeding.
And in episode 12, we see Bishop with tears in his eyes when Celine says Aidan keeps running away, not coming back.
...right after he practically said that he turned Aidan because he loved him.
And in episode 13, at the end of the Boss Fight, Bishop reaches up towards Aidan's cheek, almost a caress, as Bishop is being beheaded BY Aidan. Hard core.
At one point, Bishop says something to the effect of he wasn't going to allow Aidan to (live to) hate him anymore.
And now in season two Aidan's seeing hallucinations of Bishop, and Bishop essentially tells him he never could've killed him anyway.
Fridge Horror: Normally Aidan strongly opposes vampires feeding on people, but he does nothing to prevent the a woman pregnant with twins from being bitten. (Heck, he even throws the table she's tied to.)
Bishop says earlier that she was compelled, referring to a vaguely explained mind power of vampires that can be used to make people obey them. Usually this is fairly harmless, but can cause grivous mental damage. Aidan's disregard for their lives could mean that if the woman was mentally conditioned to the point that she wouldn't resist someone chewing on her radial artery, she and her children were, to all intents and purposes, already dead.
Les Yay: Sally tends to come off as this on occasion. For instance while talking at Emily, Josh's sister, she says she could make her feel happy. And when Nora comes over, Sally's promptly quips that she's hot and had nice boobs. And when Nora sees Sally for the first time, she quips that Josh never mentioned she was so attractive.
Magnificent Bastard: Bishop earns this title after he has the Dutch drink juniper, then kills them when the rigor mortis kicks in the next night.
Moral Event Horizon: Bishop has Marcus violently kill two boys who were picking on Bernie, conveniently after a recently turned Bernie talks about how they'd never pick on him now. Aidan doesn't know this, and so kills Bernie, believing that he's shooting the dog. Yes, the entire plotline and three dead children was so that Bishop could drop another metric tonne of angst on Aidan's already heavy load.
To a, perhaps, lesser extent Bishop turning Rebecca. After teaching her the basics, he basically turns her loose... but note he also promptly guides her right back to Aiden presumably so that Aiden gets more angst. So basically, he intentionally traumatizes and creates a monster for no other purpose than to prod Aiden. He doesn't care about Rebecca in the least other than as a pawn.
Of course then there's... Celine whom he rapes and blackmails in order to gain some leverage over Aiden by being able to force her to disappear.
Liam using Erin to go after Aidan under the guise of reuniting her with Josh and Nora comes up on it. But he roars over it full-throttle when he kills her in the hospital.
Nightmare Fuel: For many episodes, we've been teased with Josh's werewolf form, either being heard offscreen, bits of the transformation showing and so on. Then in Episode 8 we finally see Josh's werewolf form, a starved, mangy looking, four-legged wolf abomination that looks NOTHING like the original British version of the werewolf. All rendered in CGI that is of higher quality than most other Syfy Channel shows and films. It also tries to attack Sally, but of course, can't because she's a ghost.
Darla, the little girl who invites Aidan to drink from her by handing him a pair of scissors. The implications are just so disturbing. A starving Aidan is so freaked out by her that he flings himself across the hallway and flees from the building.
Flayed Henry. And those poor girls ...
Sally in 2x09 and 2x10 while possessed/being the Reaper.
Potentially the look of sheer happiness - something we've never see on her before - when Nora talks to Josh about how she would rather be a wolf than be human.
After Bishop poisons the Dutch, Aiden throws a table at him to slow him down while he rescues one of the Dutch. Alas, there happens to be a pregnant woman strapped to the table at the time.
Henry's imprisonment of his girlfriend, which has more than a few similarities to RL cases where husbands have kept their wives from leaving their homes.
The TV spots of season 3 have often shown glimpses of a werewolf that appears to have half its face horribly scarred, making it look even scarier than the werewolves previously shown.
Squick: The scene where Aidan and Rebecca lay together, drenched in each other's blood.
The revelation that Josh's werewolf form eats its own feces.
The infamous season 2 scene Where Aiden compels two young women to offer themselves to a skinless Henry so that he can messily feed on them to regrow his skin. Only for them to start to realize midway through and be horrified at what is really going on.
Strawman Has a Point: While most of Ray's ideas are... extreme, one has to give him a little bit of credit for having the desire not to let his lycanthropy control and define him as a person.
Uncanny Valley: Is it possible to be this in real life?? Suren's face is practically two-dimensional!!
Perhaps intentionally done since the show may be making the point that given such longevity and power, vampires may start finding difficulty emoting and otherwise 'being human'.
Cara, adorably awkward, gets shot down by Aidan and killed by his ex when she tries to flirt.
Bernie is a neighborhood boy who is bullied regularly, he is later saved by and befriends Aidan. After some mishaps he is later rejected by Aidan and ends up stricken and killed by a car. He is then turned into a vampire, and due to some manipulation on Bishop's end, ends up being killed Aidan who believes [Bernie] can't control himself.
Kenny. The poor kid suffers from Severe Combined Immunodeficiency and will have to live his entire life in a plastic room inside a hospital. Aidan agrees to turn him into a Vampire so he can go outside and enjoy life a little. Instead he turns him into a grotesque werewolf blooded vampire monster with an appetite that dwarfs Aidan's already problematic state. Aidan knows the poor kid's a ticking time bomb, but can't convince himself to Shoot the Dog.