“IT WASN’T A NIGHTMARE!” Ron yelled. “PROFESSOR, I WOKE UP, AND SIRIUS BLACK WAS STANDING OVER ME, HOLDING A KNIFE!”
Professor McGonagall stared at him. “Don’t be ridiculous, Weasley, how could he possibly have gotten through the portrait hole?”
“Ask him!” said Ron, pointing a shaking finger at the back of Sir Cadogan’s picture. “Ask him if he saw —”
Glaring suspiciously at Ron, Professor McGonagall pushed the portrait back open and went outside. The whole common room listened with bated breath.
“Sir Cadogan, did you just let a man enter Gryffindor Tower?”
“Certainly, good lady!” cried Sir Cadogan. There was a stunned silence, both inside and outside the common room.
“You — you did?” said Professor McGonagall. “But — but the password!”
“He had ’em!” said Sir Cadogan proudly. “Had the whole week’s, my lady! Read ’em off a little piece of paper!”
Professor McGonagall pulled herself back through the portrait hole to face the stunned crowd. She was white as chalk.
“Which person,” she said, her voice shaking, “which abysmally foolish person wrote down this week’s passwords and left them lying around?”
There was utter silence, broken by the smallest of terrified squeaks. Neville Longbottom, trembling from head to fluffy-slippered toes, raised his hand slowly into the air. Rowling, J.K. Harry Potter and the Prisoner of Azkaban (pp. 108-109). Pottermore Publishing. Kindle Edition.

Harry moved Ron over to one of the couches by the fire, as he was getting slightly shocky. Looked at his supposed head of house with a blank face as though he was judging her very soul…. And finding it wanting.
She remembered well the last time she had seen a look like that. She had been in the headmaster’s chambers with James, Sirius, and Severus after an incident involving the Willow, Remus, and James having to save Severus’ life from Sirius’ so-called prank. Severus had that same look when she had agreed to abide by the slap on the wrist Sirius got for the incident.
And with a shock, she remembered the other face she had seen it on after that mess was Harry’s mother’s, Lily’s, face after gossip got around that the boys got off with yet another slap on the wrist for endangering a student.

Oh, God, how could she have not seen how much of her was reflected in her son’s face before? How blinded by Albus’ words on his being his father’s son?

She watched him give care to his friend, then give a gimlet eye to the squirming Longbottom boy. The same stare that had James confessing all his sins to Lily. “You will, of course write a confessional to your gran, so that she might met out payment for them?” He demanded in James’s voice, but with Lily’s wording to the Longbottom boy. And by this demand, she knew it would get done and how Augusta would take the confession. And the penance the boy would have to pay and sighed.

She then watched as he walked up to the guardian portrait of Sir Cadogan, all puffed up and proud, and groaned at how he, as a personification of Lily, was going to take this.
She watched as he pinned the man/boy portrait in place facing forwards with his wand against the man’s middle, then, without words, started to heat the portrait. And let it scream, quoting the portrait’s words back for all to hear; “He had ’em! Had the whole week’s, my lady! Read ’em off a little piece of paper.” Burn and screams. With winces all around. “But a puffed-up rooster couldn’t use the common sense the gods gave a turnip to tell this was wrong.” And lifted his wand from the now holed painting where his crotch used to be. And every guy, poltergeist, and male ghost, who had been watching cringed.

“Begone, you foul beast, cotton eyed joe. Thy grasp on this plane faded long ago. From whence you came, there you shall go. I seal thee away, cotton eyed joe.” All Lily in that statement as he waved the fallen painting away via the elves who replaced it with a portrait of their Founder, now awakened.

Oh God, Lily had returned in the form of her son, and she wasn’t happy at all.