How could Sir Cadogan give Neville the passwords? [duplicate]

Question

In Chapter Twelve of Prisoner of Azkaban we find the following passage:

They turned into the corridor to Gryffindor Tower and saw Neville Longbottom, pleading with Sir Cadogan, who seemed to be refusing him entrance.

"I wrote them down!" Neville was saying tearfully. "But I must've dropped them somewhere!"

"A likely tale!" roared Sir Cadogan. Then, spotting Harry and Ron: "Good even, my fine young yeomen! Come clap this loon in irons. He is trying to force entry to the chambers within!"

"Oh, shut up," said Ron as he and Harry drew level with Neville.

"I've lost the passwords!" Neville told them miserably. "I made him tell me what passwords he was going to use this week, because he keeps changing them, and now I don't know what I've done with them!"

This situation seems a bit strange. Sir Cadogan is refusing to allow Neville into the common room – even though Neville is a Gryffindor – because he doesn't have the password. And he's obviously not telling Neville the password. Yet we then immediately find out that he has previously told Neville all the passwords in advance. If he's not supposed to tell students the password even if they are from the correct house, how did he give Neville the whole list? And if he is allowed to give students the passwords then why couldn't he just tell Neville the password when he forgot it? (And what would be the point of a password in the first place?)

And even if we interpret "A likely tale!" roared Sir Cadogan. as saying that Sir Cadogan forgot that Neville was a Gryffindor but had known that when he originally gave him the passwords, it would still render the password system mostly pointless, as the portrait would simply give any Gryffindor the password.

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Edit

I'm not sure why this would be a duplicate, given that the question this is supposedly a duplicate of explicitly states that it is a follow-up to this question, and the only answer there is mine and it doesn't answer this question. Essentially, what happened was that I asked a question and someone tried to answer it. That person then realized that he/she did not know enough background information to give a complete answer to this question, at which point that person asked for the background information and I supplied the information I had been working with when asking my question.

Answer 1

I think you've summed it up best when you said "This situation seems a bit strange" in your question, as seems to be most goings on in Hogwarts. There's two things to address here: how are passwords distributed under normal circumstances and is Sir Cadogan in breach of the standard practice?

Annoyingly, I can't find anything concrete on how passwords are initially distributed within Hogwarts. The characters of the books usually find out the Gryffindor Common Room password from a prefect or a fellow student. I think it's safe to assume that at least the headmaster/mistress and head of Gryffindor can get the password from the Fat Lady, who (given a certain level of sentience) can set the password herself, which they then distribute to the prefects who go on to tell the new and returning Gryffindors. I say this as this question seems to successfully argue that the guardian to a common room is in charge of the password.

Given this premise (which I think is reasonable), it would appear Sir Cadogan is within the rules of password setting. However, read this quote:

The Fat Lady's ripped canvas had been taken off the wall and replaced with the portrait of Sir Cadogan and his fat gray pony. Nobody was very happy about this. Sir Cadogan spent half his time challenging people to duels, and the rest thinking up ridiculously complicated passwords, which he changed at least twice a day.
"He's a complete lunatic," said Seamus Finnigan angrily to Percy. "Can't we get anyone else?"
"None of the other pictures wanted the job," said Percy. "Frightened of what happened to the Fat Lady. Sir Cadogan was the only one brave enough to volunteer."
_{Harry Potter and the Prisoner of Azkaban - Chapter 9: Grim Defeat}

It sounds like he's taking a very liberal approach to his new responsibilities, which is causing annoyance to essentially every Gryffindor. Given his quite irregular handling of his position, combined with his eccentric demeanor, I think he likely gave Neville the password list in breach of the standard protocol for portraits. This ultimately led to him being fired as the portrait guardian of the Gryffindor Common Room.

As a further point, Sir Cadogan is ultimately proved as grossly inadequate for the job when he doesn't show any remorse (or rather, doesn't see his error) for having admitted Sirius to the Common Room.

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!"
_{Harry Potter and the Prisoner of Azkaban - Chapter 13: Gryffindor versus Ravenclaw}

To conclude...

Sir Cadogan was within standard protocol by setting his own passwords for the Gryffindor Common Room. However, his interpretation of the rules surrounding setting a password (namely, being able to change it at his own discretion), combined with his extremely eccentric personality, meant that in order to maintain repetitive password changes he did break the rules by telling students (in particular Neville) his password. This did, in effect, make the password system useless, which led to a suspected murder gaining access to the Common Room. Any inconsistency in how he circulated passwords and why he wouldn't admit Neville can be attributed to his highly unusual character profile and a break from the usual password protocols.

Answer 2

Possibly he is able to supply the password(s) to a student leaving the common room, since they will demonstrably be from Gryffindor.

And Neville took advantage of this to ask for all the passwords earlier in the week while exiting the doorway.

Answer 3

If he's not supposed to tell students the password even if they are from the correct house, how did he give Neville the whole list?

Paintings, while not exactly fully sentient, certainly aren't automatons - they are fully capable of taking action on their own initiative.

Sir Cadogan shouldn't have given Neville the passwords in advance, and that may be why he got fired. But he was perfectly capable of doing so.

Basically, he just showed remarkably poor judgement. Given his established character, that should not come as a surprise.