The Doctor grabs Sarah Jane's hand and they run, young and beautiful and in delicious danger. And was the day of my delight As pure and perfect as I say? If all was good and fair we met, This earth had been the Paradise It never look'd to human eyes Since our first Sun arose and set. And is it that the haze of grief Makes former gladness loom so great? The lowness of the present state, That sets the past in this relief? Or that the past will always win A glory from its being far; And orb into the perfect star We saw not, when we moved therein?
K-9 raises his head to look at the Krillitanes. Finch mocks him: "The little dog with a nasty bite. Not so powerful now, are you?" he whispers. K-9 replies by shooting the vat of oil, which explodes all over the shrieking, burning Krillitanes.
Mickey leads the children away from school, and into safety. That's my boy.
The Krillitanes wail and writhe. "Burning!" screams the lunch lady. "You bad dog," hisses Finch. "Affirmative," says that good dog; that mechanical wonder. And the school explodes.
The assembled children cheer and applaud, because schools blowing up is super-awesome on TV, always. Rose and Mickey join in, hugging and giggling. "Yes!" says Kenny, and Melissa asks if he had anything to do with it. He nods and says he did, and her jaw drops: "Oh my God. Kenny blew up the school! It was Kenny!" The kids all cheer harder and chant his name, patting him on the back.
The Doctor and a very upset Sarah Jane stand apart from the celebration. "I'm sorry," says the Doctor, and she quickly cuts him off: "It's all right. He was just a daft metal dog." She looks back at the school. "Fine, really," she says, and then bursts into tears. This metal soul between them; this link between the past and the future, between childhood and what comes after. This metal dog she put between herself and emptiness. Her only friend. It is hard to be Sarah Jane Smith. Wait until it's you. The Doctor puts his arm around her; Rose turns back to look up at the school with Mickey. If this show turns over Doctors and Companions, and she's not special, then what keeps her from turning into Sarah Jane Smith? It wasn't that they were so different: it was that they were exactly the same. She won't watch that happen: it's too intimate.