The theory is typed in full here:
http://mortenavida.livejournal.com/492214.html
But incase that gets deleted or goes friends only I'll quote the main part.
Anthony Caruso (Clarkstown South High School) wrote:
So obviously from the Topic title this is about the possibility of Professor McGonagall being a spy for Voldemort. I know it sounds far-fetched and believe me, when I first read this theory in a Mugglenet Editorial I was so astounded. I mean, McGonagall is one of my favorite characters and she is soo good so how could she be a spy for Voldemort? But then I read the editorial and I was blown away. It really got me thinking that it could actually be true. So I'm just going to post some highlights and evidence about it from the editorial and some of my own ideas.
"But – she’s [McGonagall] so wonderful! We love her and cheer for her – her crotchety old spirit, strength of character, biting wit, her constant support of Harry even under pressure, and the fact that she is just plain cool... A bit like Mad-eyed Moody in GOF. Jo doesn’t mind giving us a favorite character whom we respect and chuckle behind our sleeves at (The Amazing Bouncing Ferret, anyone?), and then smashing our castle brutally. And McGonagall isn’t a person. She is a character. A very cool character, but a character invented by an author who has proven that she is the master of the red herring.
By the way, did you know that McGonagall and Tom Riddle went to school together?
McGonagall is two years older then Tom Riddle, according to the Harry Potter Lexicon, which dates McGonagall’s birthday in 1925 and that Voldemort’s in 1926 or 1927. Therefore they both attended Hogwarts and were within two school years. It’s safe to assume that they were both prefects. They must have known each other. This seems to be very important information - why haven’t we been told? The only reason we wouldn’t be told was if JK Rowling didn’t want us to know. And why wouldn’t she want us to know something so important but seemingly so innocuous? Perhaps because it isn’t innocuous. There is a parallel nature to their lives that gives two foundations: one, it gives ample opportunity for them to meet and become connected, and two, it leaves doors opened for later explanations of events – such as the connection between Voldemort’s job at Borgin and Burkes and McGonagall starting at Hogwarts, which happened a year apart.
Certainly, we cannot convict McGonagall on the grounds of “having opportunity to side with Tom Riddle.” But although we all love McGonagall, has she ever done anything that would disqualify her for being a Death Eater? When we rush to defend her, citing cases of strength of character and witty retorts, do we ever have in our hands actions – things that she herself has committed – that place her firmly on the side of Dumbledore? In other words – what, officially, prevents us from believing that McGonagall is a spy? And is lack of evidence for a good McGonagall enough to convict? After all, none of her actions show any leaning towards evil, although noticeably neutral. Nothing she’s done is actually suspicious... Or.... perhaps it is.
Perhaps the fact that she appears at Privet Drive that fateful day before Dumbledore. The fact that he was not anticipating her arrival, although it “amused” him. Process that. Dumbledore didn’t send McGonagall to Privet Drive. So what was McGonagall doing all day – the most important day in Wizarding history – sitting on a stone wall? Especially when we find out that she had no idea that Harry was arriving there. How did she know that Dumbledore was going to be at Privet Drive – or did she even know? And if she didn’t know, why was she there? Why is she so angry – angry – at the celebrations taking place? Why does Jo attach adjectives to her like “coldly”, “piercing”, “sharply”, and “angrily” all in the same two pages as they are discussing – not the death of Lily and James – but the demise of Voldemort? Why does she become almost out of control at the idea of Harry living with the Dursleys? And why are there so many unanswered questions about McGonagall from this one scene?
It’s not only the opening chapter of PS/SS that cast a shadow over McGonagall. The trio goes to her with the information that the Philosopher’s/Sorceror's Stone is about to be stolen. When Harry wants to talk to Dumbledore and tells her it’s secret, she’s “cold” and answers him sharply. Why the negative response? But that’s nothing compared to her reaction to their knowledge of the Philosopher’s Stone. She is extremely flustered, dropping things, reacting with “suspicion and shock” that these children know such a well hidden secret. Which makes me wonder – if these children know such a well kept secret, isn’t it less guarded then originally thought? And if that’s the case – shouldn’t she at least mention it to Dumbledore? Considering that she’s his second in command, the fact that she doesn’t even notify him is very strange.
Remember her reaction to Ginny’s return – alive and well – in CoS?
“I think we’d all like to know [how she got out alive]," McGonagall said weakly.
Weakly. She’s certainly in a bit of shock. Remember who was with Barty Crouch Jr. when the dementor administered the kiss in GoF? Isn’t it strange that one of the most powerful witches of her day couldn’t prevent that happening in the same room with her? Re-reading the books, I’m struck by how often McGonagall’s actions are neutral, and how often her words could be taken to mean so many different things. When McGonagall first hears of Dumbledore’s murder, she sinks into a chair in shock and gasps:
“Snape...We all wondered... but he trusted... always... Snape... I can’t believe it...”
Substitute Voldemort for “he” in that sentence and listen to the implications – a bit shocking how easy that was, isn’t it?
Even beyond double meanings, though, the final scene with Harry and McGonagall is disturbing. Harry will not tell her about his trip with Dumbledore, and her reaction – rather then grudging acceptance of his loyalty to Dumbledore – is anger and frustration. But she too is supposed to be loyal to Dumbledore – and considering that he’s just died, the fact that she is prying into his personal information through Harry seems at best inconsiderate, and at worst – treacherous.
J.K. Rowling is playing a very tight game here. She has to give us enough very cleverly hidden clues so that when the truth is revealed, we believe it despite the shock and horror, because we can return to the older material and find the weaker scent. However, if there is too much evidence and paper trail, it’s ferreted out and there is no surprise. Is there lack of evidence? No. Is there abundance of evidence? Obviously not.
Alright, I admit that there isn’t any conclusive evidence against McGonagall. But let’s do a bit of literary role playing. You are J.K. Rowling. You are starting to plot out the Harry Potter books, and you decide, for kicks, to create a spy. You want it to be revealed at the end of the seventh book, so for six books you have to hide him from your readers prying eyes. You begin to lay out the game plan, with this thesis – if there was a spy, what would he look like and how would characters around him behave? He would be:
* Trusted by Dumbledore – high up in command.
* Trusted by Harry and his friends.
* Trusted by the readers.
* No doubt about his/her loyalties.
* There would need to be someone or something to distract people (readers and characters) from thinking about him/her at all – say, a more obvious target.
* Someone with ties to Voldemort that were discreetly hidden.
* Mild hints scattered that were recognizable from hindsight, but barely visible at first glance.
* Nothing to disqualify him/her – random acts of goodness – that would have to be explained away.
Is there anything I missed?
If there was a spy at Hogwarts, his/her character would be developed in exactly the same way as McGonagall’s character. Catch that?
If JK Rowling created a spy for Voldemort, she would have to create the character in the same way she has created McGonagall.
I’d say that that’s an indictment.
It’s still all guesswork and whistling in the dark, of course. But then, if it was anything else and we could prove it, JK Rowling wouldn’t be a master at her trade, now would she?"
Also Think about the irony. Snape, the Slytherin, turning out to be a good guy and McGonagall, the Gryffindor, turning out to be a bad guy? Plus JKR said there are Death Eaters from Ravenclaw, Hufflepuff, and Gryffindor so why not McGonagall?
PLUS, McGonagall is head of Gryffindor and WAS head of Gryffindor when the Marauders were at school. What if she saw Peter, a vulnerable, weak, little boy who didn't fit in even with his own friends, and decided he could be easily persuaded so she pushed him to the Death Eaters? She'd be in the perfect position to influence him as head of his house.
[I'm adding people on here, by the way, that added things that had to do with the theory]
Jessica Irish (UC Davis) wrote:
i think this is really interesting, and certainly worth thinking about. the one thing that bothers me is that mcgonagall gives off such an aura of goodness and rightness (if you will). i think jo rowling is amazing at playing with characters' loyalties, but there are certain characters that just give off an innate aura of reliability and trust. this theory is hard for me to accept in the same way that it would be hard for me to accept a theory that fred and george were working for voldemort. they're just too good.
so i would say that even though the theory is convincing on a purely analytical level, there is too much emotional goodness in mcgonagall's character for me to condemn her as a spy.
although it was a little odd that she asked harry what he was doing with dumbledore the night they went after the necklace horcrux. hmmm...
Anthony Caruso (Clarkstown South High School) wrote:
Also, new evidence against McGonagall:
McGonagall let Harry onto the Gryffindor Quidditch team. What is so significant about this? Harry was the youngest seeker in a century and first years aren’t even allowed to play on their house teams. When has McGonagall ever shown any inclination to break rules or traditions? Never. Yet she admitted Harry to the team. What happened that first year? That very first Quidditch game? Harry was nearly killed.
Fawkes left the school for good at the end of the book six. Fawkes goes to people /is attracted to people who are loyal to Dumbledore and have shown loyalty to him in the past. If McGonagall was so loyal to Dumbledore, like everybody believes, why didn’t Fawkes stay behind at the school with her?
Kimmii L (Glendale Secondary School) wrote:
With Fawkes. Fawkes went to who ever was the most loyal to Dumbledore WHEN HE WAS ALIVE...once Dumbledore died, I believe Fawkes leaving had some significants...once his master is gone, it goes. However it is possible it would go back to Harry when he needs him the most...because Harry always did support Dumbledore more than McGonagal I think. I mean, Dumbledore told Harry about the Horcrux's but not McGonagal...and McGonagal didn't seem to mind telling HARRY'S class about the chamber of secrets...knowing that Harry, Ron, and Hermione would more than likely try to figure something out. So when looking at this it does become suspicious....
Anthony Caruso (Clarkstown South High School) wrote:
She said it in the Mugglenet/Leaky Cauldron Interview. Here's the exact quote:
ES: But there aren't a lot of Death Eater children in the other houses, are there?
JKR: You will have people connected with Death Eaters in the other houses, yeah, absolutely.
ES: Just in lesser numbers.
JKR: Probably. I hear you. It is the tradition to have four houses, but in this case, I wanted them to correspond roughly to the four elements. So Gryffindor is fire, Ravenclaw is air, Hufflepuff is earth, and Slytherin is water; hence the fact that their common room is under the lake. So again, it was this idea of harmony and balance, that you had four necessary components and by integrating them you would make a very strong place. But they remain fragmented, as we know.
Except that you should note that Kimmii L got it wrong for it is the ghost history teacher that tells the class about the Chamber of Secrets not McGonagall but since he isn't in any of the movies she gets the job.
And no one has ever really felt some sort of instict against her in the books. 
