Almost every plot was thickened on The Vampire Diaries this week.

More than any episode in memory, "Disturbing Behavior" gave each vital character a chance to shine. Or connive. Or ponder her feelings for her blood-thirsty boyfriend's brother. Or temporarily murder his best friend in town because everyone was getting on his nerves.

Oh yes, Stefan is about to re-enter a Mystic Falls with a whole lot going on. Let's run it all down, shall we?

In Katherine, we... trust? Is that even the proper question to be asking these days, whether or not we trust Katherine? As we debated at length in last week's Vampire Diaries Round Table, it's impossible to keep track of this Nina Dobrev-portrayed character these days. What has she been up to? Why was in Chicago? What plot is she hatching this time around? Will it come together in a more sensible manner than her season two storyline?

There's still a fear that Katherine is being used more as a plot device than anything - appearing when convenient to shake things up and move characters around - but now that she's an integral part of ongoing arcs again? I'll believe, Kevin Williamson and Julie Plec. You must have a coherent plan in mind. Don't let me down.

I'm just a girl, looking for a partner in crime. Katherine, dear, you are so much more than that.

Crossing a Caro-line. First off, how freaking awesome has Caroline become?!? Painted as little more than a bubbly blonde when human, her confidence and swagger has grown every week as a blood sucker. She's still super sweet (see scenes with Tyler, and then worry about what might happen if these two have a baby...), but she can also get angry and, forget The Hulk, you do not want to see Caroline when she's angry.

Damon discovered that fact this week via a scene that still has me cheering. What fun it was to see Caroline go after this Salvatore, partly due to her reasoning: yes, Bill Forbes tortured his daughter - but she's still his daughter. There's still love there. She still bought him that expensive shirt. Bravo to The Vampire Diaries for creating a complicated, layered relationship between parent and sibling here, although I must disagree with Bill's final assessment: Caroline and her new attitude will be just fine.

Poor Anna. That's almost all I have to say about this storyline. It was heartbreaking to watch her cry and utter about how she's "all alone" when Jeremy told Bonnie about his little ghosts-of-ex-girlfriends-past problem. Still, I doubt forcing me to admit that I teared up over a dead vampire is the sole purpose for this development.

Anna feels a "darkness" when Vicki is around? And when Bonnie tried to summon a necklace-related spell? What the...?!? I typically enjoy trying to make predictions, but I'm at a loss on this one. I can't imagine what ghost Vicki is up to. Guess I'll be forced to keep tuning in every week to find out. Oh well. That's a tad bit less painful than what Gloria did to Stefan. Speaking of which...

Silly Stefan. He may wanna leave all future scheming up to the other Salvatore sibling. Stefan was a bit too trusting of Gloria and Rebekah here, not taking enough time to feel them out and see if he really could hint that he isn't on board with Klaus' master plan. Granted, Elena was in trouble and it's hard to think rationally when trying to save your one true love, which was another development from the episode:

Yes, that would be Elena, not Rebekah. Stefan's memory is intact and he is still putting Elena above all else. Romantic? Absolutely. Dangerous to both? Clearly. Impressive, considering how Claire Holt looked in this dress? Yes, very.

Councilman Alaric. I love it as much as I still hate how everyone has shortened his name to "Ric." The guy has a ready-made tagline already if he ever needs to campaign (A Man for the People. Literally!) and a perfectly understandable reason for joining the Council: his girlfriend was killed by a vampire, his wife was obsessed by vampires, his BFF of a vampire has a tendency to briefly murder him... can you blame Alaric for realizing that someone in Mystic Falls has to look out for its actual citizens?

Those citizens will be in even more danger next week, although the official preview for "The Reckoning" makes it clear that only one of them will truly be threatened by Klaus and Stefan.

All around, a fantastic episode of The Vampire Diaries that included almost every character and left me with just four questions:

1. Where the heck was Matt while everything was happening? Must have been a busy day at The Grill.
2. Why doesn't Klaus just compel Stefan in order to learn his true intentions?
3. What kind of boring name is Michael for a vampire hunter than even leaves Klaus quaking?
4. Bill must be the first person to ever refer to Damon's technique as "lazy," right? I don't recall any women complaining.

Matt Richenthal is the Editor in Chief of TV Fanatic. Follow him on Twitter and on Google+.