Was Cormac McLaggen created due to criticism of the black and white nature of nice/nasty characters at Hogwarts?

Question

Cormac McLaggen was a bit of an idiot, rude and a bully, the first time we see these traits in a Gryffindor student. He also only appears (despite being an older student) in The Half-Blood Prince. Out of universe, has JKR commented on his creation? Was he created due to the simplistic Gryffindor good / Slytherin bad characters in the earlier books?

Answer 1

We don't know, but probably not.

I've searched through Pottermore and the JKR interview archives, and the only even vaguely relevant quote I found was one which said she called him McLaggen because she liked the name:

You have to be careful if you get friendly with me because you tend to turn up in my books, and if you offend me, you often turn up as a nasty character. I found the name McLaggan the other day, which I think is a great name. There is a McLaggan in book six because I thought that it is a surname that is too good to waste.

_{-- JK Rowling, interview}

Of course, this doesn't really tell us much about why she created the character.

However, there are other reasons for why this particular character should have been a Gryffindor. As mentioned on Pottermore (I don't know whether or not this particular page was written by JKR):

You’ve got to love Cormac. Well-connected and entitled, Ron’s nemesis firmly believes he will get both the Keeper position and the girl. Little does he know he’s really just a pawn for Hermione as she struggles with her feelings for Ron.

This neatly summarises McLaggen's role in HP and the Half-Blood Prince. And in order to be able to compete with Ron for a Quidditch position as well as for Hermione, he had to be Gryffindor. I imagine that that was a more important consideration in the creation of the character than the desire to have a Gryffindor who wasn't clearly a 'good guy'. Perhaps JKR thought after the fact that it was rather neat to have a dislikeable Gryffindor somewhere in the series, but I doubt that was the main reason she put McLaggen in that House. His main purpose is to be a foil for Ron, and for that reason he had to be a wannabe Keeper for the Gryffindor Quidditch team.

Answer 2

Playing devil's advocate to the previous answer, I'm going to say...

Probably

I don't think it's an accident that in HBP we get Cormac McLaggen, an arrogant, swaggering Gryffindor, who to be frank hits all the negative stereotypes about Gryffindors, and Professor Horace Slughorn, a friendly, helping Slytherin.

McLaggen thinks that he's just the best at everything. He can get the girl, the Keeper position, and he knows best (see: where he spends all his time 'coaching' the other Gryffindor players and winds up knocking Harry out). In every sense he's a big dumb blundering oaf.

And then the other side of the coin is Slughorn, who fully defines the idea that ambition does not necessarily mean 'wants to rule the world by any means necessary'. Slughorn, rather, has a true eye for talent and cultivates connections to help said talented students get a leg up. He always does get something back out of the deal, but that's just par for the course. And he truly does greatly regret the one time (we know of) that he helped someone truly evil- Tom Marvolo Riddle, aka Lord Voldemort.

I do think JKR had at least it in the back of her head to defy stereotypes about the Houses, because prior to that all we really had was that 'Gryffindors are good, friendly, and great' and that Slytherins were all scum.

Answer 3

Not likely

Cormac is not a bully as such, but yes, he is an arrogant and vain person who expects preferential treatment based on his connections. But he isn't the first Gryffindor portrayed in less than favorable light, and in my opinion his purpose in the story is more complex than just adding a bad Gryffindor to the mix.

1. After her first book JKR was already done with black-and-white characters:

In the books preceeding HBP we already got introduced to less than perfect characters from Gryffindor house - Peter Pettigrew for one, and in Harry's fifth year he got a peek into the memories of Snape, presenting him with the favorite pastime of James and Sirius at age fifteen - bullying.

Starting from the second book, we got less of the overly simplistic slytherin-bad gryffindor-good approach and we're deep into grayscale. Plenty morally ambiguous characters appear, like the fraudulent Lockhart, the easily fooled Dippet, Fudge, who locks the innocent Hagrid in Azkaban and gambler Ludo Bagman. As far as we know, none of these characters identify as Slytherins and their affiliation to the Hogwarts houses is irrelevant to the story in most cases.

2. The role of Cormac McLaggen

Cormac is just another one in a long string of characters whose purpose is to teach Harry a lesson about human nature and right and wrong choices. (and as @Rand writes he could have been a member of any Hogwarts house, if not for his two main scenes in the book, both of which required him having a connection to the Gryffindor quidditch team.)

Cormac demonstrates to Harry how things work outside of school. After all, books 5-6 represent the process of entering adulthood: With Hermione's help Harry gradually realizes that school and teachers exist to prepare the kids for what is 'out there' - that is, for their future career and life. Fifth year is OWL and career advising year. In sixth year Harry starts the advanced courses needed for his chosen profession and starts the prep for his NEWTs.

But at the same year Harry realizes that perfect OWLs and NEWTs aren't everything, that's not how society works - there are also other, easier ways one can advance a career. Talent in itself isn't enough without connections: an useful recommendation at a right time and knowing infuental people can make all the difference. That's why we have the Slug Club and Cormac McLaggen in the sixth book. After all, it's evident that Cormac was chosen to be a member of the Slug Club because he is extremely well connected:

“Now, you, Cormac,” said Slughorn, “I happen to know you see a lot of your Uncle Tiberius, because he has a rather splendid picture of the two of you hunting nogtails in, I think, Norfolk?” “Oh, yeah, that was fun, that was,” said McLaggen. “We went with Bertie Higgs and Rufus Scrimgeour — this was before he became Minister, obviously —” ~ Harry Potter and the Half Blood Prince

Conformism, nepotism and corruption in general aren't exclusive to the members of Slytherin : they exist in every house and every buerocratic structure. After all, Cormac just confirms what Percy Weasley already demonstrated to Harry: that people are often motivated by self-interest, even Gryffindors who grew up in 'good' families. Just remember his letter in which he advised Ron to dissociate himself from Dumbledore and Harry Potter's 'bad reputation':

I shall say no more here, but if you look at the Daily Prophet tomorrow you will get a good idea of the way the wind is blowing — and see if you can spot yours truly! Seriously, Ron, you do not want to be tarred with the same brush as Potter, it could be very damaging to your future prospects, and I am talking here about life after school too. ~(Harry Potter and the Order of the Phoenix)

Cormac is Harry's caricature: could've been that famous and rich Harry Potter without the influence of people like Dumbledore, Arthur Weasley and McGanagoll would've been corrupted, choosing the easy life Slughorn showed to his favourites: conformity and partiality instead of his trademark uncompromising attitude to do the right thing.