Where do we even begin this week?

In one of the most dense episode of the season, The Vampire Diaries viewers learned why Damon holds such a grudge against Stefan; discovered a great deal about a new character on the show; and even got to witness Stefan and Elena in bed.

It was a sexy, engrossing, suspenseful, educational hour of television. Catch up on "Children of the Damned" via our detailed recap and join us below for an in-depth review of the episode...

How great is Nina Dobrev as Katherine?!? The actress made us forget about Elena during the opening scene. Whether Dobrev has been consulting with Ian Somerhalder for tips on how to act evil is unclear, but this much is not: she relished taking on such a new, different role. It was also startling to see Damon as a hesitant, fearful vampire. It makes us realize how events have changed him so much in the last 135 years.

And how did those events begin? We got to actually see Damon and Stefan during the height of their affection for Katherine. True to the modern-day situation, the former brother was clearly more smitten with this mysterious brunette than his sibling. Somerhalder made us truly feel Damon's pain when Katherine was taken away, but we have two questions that resulted from these flashbacks:

1. Both brothers were knowingly sleeping with a vampire, and knew of the other's bedroom dalliances with her? We wonder if we'll ever go all the way back to when these relationships began, as it would be interesting to see how such a set-up evolves.
2. When did Katherine turn them? This was the only confusion we were left with when the episode concluded.

Do you believe Alaric's story? He told Stefan his wife led him to Virgina because she was a history buff and had read about the area's vampire connections. She was then killed by Damon, but her body was never found. Seems plausible all around, right? And goes along with the quick flashbacks we've seen of Alaric's life. Still, he seems to be withholding something, doesn't he?

What will happen to Bonnie? Because Ben is a new vampire, we can forgive his sloppiness. Did he really bare his fangs and grab Bonnie in public? Hard to believe no one saw him apprehend our favorite young witch, but Bonnie really has no one to blame but herself. She acted calm and cool when she first realized Ben was a blood sucker, but that mad dash for the door was a mistake.

We now come to Anna. Malese Jow has done a great job with this role already, as the character has been perfectly worked into the town and ongoing storylines. She's the one that turned Logan (isn't it great when a show remembers loose ends and ties them up in a logical manner?) and she's the one with the same goal as Damon:

Unlock the tomb. It's safe to assume this is so she can rescue her mother, Pearl.

Other questions/observations from an outstanding episode:

• Emily made it possible for Katherine and Pearl to walk around in the sunlight. Did she also create Damon and Stefan's rings?
• Damon ran away from the Confederate Army. This just hammered home the point that the driven, carefree, confident vampire we know today was once a meek individual.
• Sorry, but no one does karaoke on the first date.
• We loved when Damon approached Elena during "family night" and asked for the truth about Stefan. He didn't compel her. He simply wanted to trust her. He's getting easier to sympathize with this lonely creature, isn't it?
• First, Damon. Now, Anna. Elena really has to stop getting herself kidnapped.
• Damon seemed almost ashamed by his action near the end of the episode, didn't he? Might he finally realize the lengths to which he's going for Katherine, including threatening her doppelganger's life, might be a tad extreme?
• Was Anna a vampire when we saw her as a young child? We assume the answer is no, which leads to an important question: Who turned her and when?

Catch up on the latest Vampire Diaries quotes by following our link, get an early look at next week's episode and then chime in below: What did you think of the episode?

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