In sequence, Devon is getting a diaper check, which he then protests against, since he's obviously old enough to be able to say something about it. Sana gets angry, because she still views him as her pet/baby doll, then punishes him for saying otherwise.
The last picture has a lot of psychological madness involved. Devon is curled up in her embrace because (even though he protests against his treatment) he's become very dependent upon her and doesn't want to upset Sana. He's still grieving his lost freedom, after all these years, but he can't bring himself to hate her.
Sana is starting to see the way he's been treated and how he's become dependent. It's much different from when he first showed up and it makes her rethink her image of him. From now on, she'll try harder to remember that, despite the games they used to play, Devon isn't really a baby.