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.
Eben is the leader of the witch hunters. He's bad enough when we first see him in a flashback that reveals that he and his men murdered the members of the old Circle by pretending to want peace and tried to kill John Blackwell, but he gets even worse when he turns out to have survived the fire, only with nasty scarring, and proves bent on killing every witch alive, even those who have never heard of him, for absolutely n' good reason. He doesn't bat an eye at using magic provided by a resurrectedandpsychotic Nick to brainwash Cassie into trying to kill her father and to escape an attack by the Circle that should've killed him outright. Later, he summons and absorbs multiple demons for their power, no doubt driving him even crazier. This is after he sacrifices one of his own men to a demon and using him to lure Blackwell and the Circle into a death trap that just barely fails. According to another witch hunter, he's even killed off Isaac. Then he kidnaps Faye, fully intending to murder her and her covenmates.
We also have JohnBlackwell. Season 1's finale, "Family," reveals his master plan to use the Crystal Skull to kill all witches without Balcoin blood and create a truly dark Circle. He even tries to kill Adam, who's already dying from the spell, in front of a helpless Cassie and Diana.
Fanon: There is no indication that Charles and Elizabeth were actually married, but she is generally referred to as Elizabeth Meade.
Fan-Preferred Couple: Cassie and Jake or Faye seem to be more popular than Adam where the show seems to be leading us. Also Faye and Diana have one based on their Foe Yay.
Faye and Diana to a ridiculous extent. Wetpaint recently ran a "who should Faye be with" poll. Only Lee and Jake were mentioned in the title and the article itself, but the poll also included Diana. Diana won with over 87% of the vote.
Jerkass Woobie: Arguably, Nick. He lost both his parents and now lives with "Jesus Freaks", his aunt and uncle. Not the most desirable thing for a teenage boy, especially one with magic powers. Then he gets possessed by a demon, drowned to kill it, and resurrected to help Eben against the Circle — only to wind up dying again when Melissa stabs him before he can kill Jake, his own brother. Just...ouch.
Les Yay: Faye and every girl. Let's break it down:
Faye and Cassie. Faye's first scene in the series involved her walking up to Cassie and saying:
"You really are very pretty, aren't you?"
She also likes to get very close to Cassie when she's talking to her.
Watch this clip. Not only do they walk with arms linked for most of the scene, but watch the last few seconds and tell me Faye isn't checking Cassie out as she walks away.
"You're a little firecracker, aren't you, Cassie?"
Faye and Diana. Like with Cassie, Faye likes to get very close to Diana when talking to here, engaging in rather more eye contact and physical interaction than is strictly necessary.
The game of truth or dare they played. Faye's took the first opportunity she got to dare Diana to take off her top.
And for Faye's truth, she is asked how many people she has slept with. Faye replies "two people". Many fans have caught onto the fact that she used the word "people" and not "guys".
Faye and Melissa.
One episode has scene between Faye and Diana talking about Melissa as though Diana is Melissa's jealous Ex-Girlfriend.
Cassie and Diana have their share of moments as well. Diana seems pretty keen on getting Cassie to join and really pushes the idea of being friends. Episode 10 even has the two of them sharing Diana's bed while Jane is away. This is now shot down, since Diana has been revealed as Cassie's half-sister.
And now "Fire and Ice" gives us Diana and Melissa. In "Medallion" Faye gives them a Portmanteau Couple Name: Delissa.
Magnificent Bastard: John Blackwell. He created a fake curse to break Cassie and Adam up because they thought Jake was dying and was completely awesome about it. He also found out about Jane's plan to kill him and switched his ring out for one of her items, thus ruining Charles' revenge against him. Oh, and he used a fertility spell on the old Circle — and slept with Amelia Blake and Diana's mother Elizabeth — to guarantee the current Circle's existence so he could use them against the witch hunters. And that's not even touching the big reveal in "Family" that his true plan all along was to kill every witch without Balcoin blood and build a Circle of pure dark magic under his control, thereby making him a Complete Monsterwithout ruining this status. Need we say more?
Nightmare Fuel: Cassie's mother Amelia's death at the hands of Charles Meade. First he drops a bottle of water on the ground, causing a the sink to start spraying water everywhere. Then he strikes a match, causing a fire on the stove. Amelia manages to get the burner turned off... just as Charles strikes another match and starts the fire again. He then causes the flames to spread, then as Amelia turns to run, she slips in the water, falling and cracking her head against the ground. She looks like she's a goner, then wakes up with a gasp of "Cassie!" and fights to get out of the flames. Charles then proceeds to burn her alive, listening to her scream in pain/horror as she realizes she's trapped. He then turns and walks away without emotion.
Romantic Plot Tumor: Ask anyone what they disliked most about the series and chances are other than Grant, it'll be the Cassie/Adam plot. Thankfully, the writers seemed to get the memo and broke them up.
Series Continuity Error: The pilot has Cassie's jacket change from brown leather to black leather in the next scene.
Ship Mates: Jake/Cassie Adam/Diana and Faye/Melissa makes it so all of the members of the circle can be paired without any outsiders.
There's also Cassie/Jake, Faye/Diana, and Adam/Melissa
Ship Sinking: "Lucky" does this for Adam and Cassie when we find out that bad things happen when they have sex. It turns out that John Blackwell made up the curse, but the ship still seems to be sunk.
Even though the ship wasn't going to happen anyway, "Crystal" does this for Cassie and Diana by revealing they're related.
Ships That Pass In The Night: A number of Fayana stories also pair of Cassie and Melissa, who out of the entire circle, probably interacted the least (except for maybe Jake and Diana)
The Woobie: It's hard not to feel bad for Cassie. She has this destiny forced upon her that she doesn't want, she has dark magic inside her that could hurt a lot of people if she doesn't figure out how to control it, and her soulmate may be Adam, boyfriend of her best friend Diana, a fact that led to their breakup — and as if that's not enough, Diana turns out to be her half-sister, whose adoptive father killed Cassie's mother. On top of it all, her father is a manipulative liar and her grandmother has been murdered, leaving her practically alone...and then Diana turns against her, blaming her for bringing their father into their lives and allowing him to manipulate the entire Circle, and leaves Chance Harbor in the finale because she can't handle having dark magic. Dear God, someone give this girl a hug.