| Quote #4
"Five points from Gryffindor," said Snape, which wiped the smile from every face. "I told you not to help him, Miss Granger. Class dismissed." (7.1.62)
Snape might be the most unfair teacher of all time and scenes with him usually reveal a lot of anger and frustration in his students/victims.
| Quote #5
Malfoy let out a low, sneering laugh.
Malfoy is a little punk, and his spiel about vigilante justice is definitely ironic, considering how much of a coward he is (see how he quits bullying Harry the second a teacher like Lupin appears, or how he rushes off after Hermione hits him, not willing to risk an actual all-out fight with her).
| Quote #6
The map was one of those dangerous magical objects Mr. Weasley had been warning him against [...] but then, Harry reasoned, he only wanted to use it to get into Hogsmeade, it wasn't as though he wanted to steal anything or attack anyone [...] and Fred and George had been using years without anything horrible happening [...] (10.3.52)
Harry's judgment is definitely biased here. Stylistically, we get a series of clauses where Harry tries to convince himself that using the Map is OK. The clauses emphasize how quickly Harry is thinking and how desperate he is to justify his decision to use the Map.