She saw how he paced, around and around, as if unable to rest. She overheard cryptic conversations between him and the portrait of the great Albus Dumbledore. How strange, that the man he had killed should still be happy to talk to him, even in painted form. She watched him interact with the other staff members and the students. She noted his absences and his presence, and that he seemed as good as a house elf at remaining unseen - she had her work cut out sometimes, to follow him.
The third eye view of the sacrifices, despair, and worry that Severus undergone, was spectacularly written! You created such a depth of character from afar with the simplest of details. Subtly beautiful!