They tried to rescue Katherine from being taken to the church and burned. But they were caught and shot. When each woke up, he was under the care of Emily, who said they were transitioning because they had Katherine's blood in their system: Damon drank it because he had wanted to, while Stefan had been compelled to do so. Each brother must feed on human blood to fully become a vampire, but neither wants to. Katherine is dead, what's the point?
However, Stefan soon goes to visit his father to say goodbye and learns a startling fact: his dad is the one that shot he and Damon. He's now utterly ashamed to see Stefan alive, in the process of transition. He tried to attack Stefan, but Stefan defends himself, unaware of his strength. He tosses his dad against the wall and he impales himself on a stake. He's bleeding. Stefan can't help himself: he feeds on his father!!!
When he returns to Damon, he feels powerful and alive. He brings Damon a human and he bites into her neck, forcing her to bleed. Damon now can't help himself and also feeds. That's the key lesson learned from this episode: Stefan forced Damon to turn.
Back in the present day, once Elena learns this, she understands why Stefan doesn't want to live: the guilt over all the people Damon has killed. After he escapes from the basement without his ring, going on a suicide mission, Elena meets him outside. She pleads with him to reconsider and tells him he has a good heart. Eventually, Stefan puts the ring on and embraces Elena. He and Damon share a chat in which Damon says two things: don't blame yourself for my actions. I own them. Also: I hate you because Katherine was only supposed to turn me.
In other storyline news:
- We learn that John is keeping an eye on the vampires that escaped from the tomb. Damon and Alaric discover that he basically controls them when they run into one of them in a house. We also later see John kill Pearl with a stake to the heart. She dies in Harper's arms and John escapes, calling the sheriff to say he has information on the vampires.
- Isobel comes back. It was a bit anticlimactic, but she showed up at Mystic Grill and said hello to Alaric to close the episode.
Source: TV Fanatic