When Mrs Medlock bluntly states that Mary's mother was beautiful and that Mary clearly didn't inherit any of her looks, the kind man who has been waiting with Mary for all those hours at the docks gently points out that children change, and that Mary may grow into them. He's probably the first grown up who's shown any kindness to her.
Martha is overwhelmingly kind to Mary from the start, even when Mary is nothing but rude to her. It's Martha's sunny attitude that ultimately helps coax Mary out of her shell.
Mary sincerely thanks Martha when she gives her a skipping rope, and asks if she wants a kiss as gratitude.
Ben reveals to Mary and the boys that Lilias used to ask him to look after her roses, and he continued to do it even after the garden was locked up.
Ben: When she went away, orders were no one were to come here. I come anyway! She gave her orders first.
Although the scene is quite tense, what prompts Colin to stand up to Medlock is when she slaps Martha and tries to fire her. Colin says that if she hurts Martha again or even thinks of dismissing her, then Medlock herself will be sent away. It's nice to see the Spoiled Brat has some affection for his caretaker.
Colin getting to see the garden for the first time, which also happens to be the first time the viewer sees it in full.
This very sweet exchange between the cousins.
Colin: Are you making this magic?
Mary: No. You are.
Mary and Dickon's Held Gaze while they sit at the swing is really cute.
Medlock's Heel–Face Turn - where she's moved to tears at the sight of Colin walking.
Musical
The Act One Finale, after being frightened, by the ghostly, albeit benevolent specters of the people she knew in India, she finds herself running into the arms of one of them, only for it to be revealed to be her father's ghost who wraps her in a comforting embrace, while Lily's ghost gently guides her to the Garden's entrance.
