I've found a new theory, Hermione and Harry are siblings! But of course i can't just say that without some evidence, but the main parts of my theory is that:
- Hermione is Harry's sister, daughter of James and Lily Potter
- Hermione knows about it
- Because she has Lily's blood in her veins, she is an important defence for Harry

NOTE:note that some sentences arn't 100% taken from the books, but have the same meaning (I read the Swedish HP books!)

There are of course some difficulties about my theory -and we are going to investigate them- but we are going to see that there are very good reasons to suspect that Harry James and Hermione Jane (H.J and H.J) are siblings.

Clues:
Hermione's behaviour around Harry.
When we read the book, we get the feeling that the both of them have a special relationship with each other.
They have something special, something unique, behind the friendship - that is not Love.
It's more easier to be seen on Hermiones side. Her behaviour in the beginning of S.S(Sorcers stone), before they became friends is very intresting. Throughout the whole series, her behaviour to Harry is very sister-like.
Harry and Hermione often thinks the same thing, this happens quite alot, they know after a quick look at each other what the other person is thinking while Ron is completely lost. Sometines they even finish each others sentences (like Fred and George).

In GoF, Hermione wasn't upset about the rumors about her and Harry. Harry was irritated, but she wasn't. When she read Rita's article, she just laughed at it. And Harry just keeps saying "no, she's not my girlfriend". Does that mean Hermione knows something that allows her to laugh at this rumor?
And in OotP, she was very comfortable with discussing about Harry's relation with Cho. Even when he told Hermione that Cho became jealous..she just said "Sorry". A friend -even a close friend would have becomed embarrased in a situation like that.
But not Hermione, she just gives him more tips, this brightens my theory even more that she can become Harry's sister.

Why is Hermione a "know-it-all"? Why is it so important for her to be the smartest student of her year? It's odd that we have just found out so little about her background: J.K.R usually often writes these kind of things in the books. For example we know that Ron is a jealous person because he had been living in the shadow of his other 5 brothers, and even because his family wasn't the richest family. We also know that Voldemort hates muggles because of his father. If Hermione knows that Harry is his brother, she wants to be as good as him too! Harry was "the boy who lived", he's infamous; so she wants to prove that she's as good as him, if not better. Atleast in classes when she can answer questions that Harry can't.

And by the way, Hermione knows abit too much about the wizardry world -and specially about Harry Potter- when she first came to Hogwarts.

In PoA: "Don't be stupid", Hermione said with a panic-stricken voice, "Harry doesn't want to kill anyone, right Harry?"
In GoF: "Ron.. Harry doesn't want to play Quidditch now.. He's worried, and he's tired. We all need to go to bed." And of course in OotP - with Rita Skeeter- about Harry's lovelife.
She even talks about James and Lily(something that no one does, except for their old friends like Lupin and Sirus for example).

Why do we know so little about Hermoine's parents? They're the parents to one of the main characters, but we know nothing about them except that they are dentists. Why? Notice that she has never said just "Mom" or just "Dad" in the books, not even once! It's always "my parents" or "mom and dad"... So it's quite weird that we know less about her parents than what we know about the Dursley's neighbours or the villagepeople in Little Hangleton!
Don't forget that we have never been informed that she, in any way looks like her "parents"! Very unusual for a writer like J.K.R!
True, we haven't been told that Hermione and Harry looked alike in any way except for their messy and wild hair and that they're around the same height. but we have been informed about someone else who had bunny-like front teeth: Petunia Dursley (Hermione's aunt if this theory is true)!

When a character (often Hermione) all of a sudden stops in the middle of a sentence (doesn't count if the person became interupted), there is often a clue for us to find. These sentences that stops in the middle usually gets this "-" sign.
SS: Hermione: "This is the best wizarding school there is! I have heard - "(Yea? Where have you heard it from?)
Hermione:"I have heard so much about you - of course, i have some books about you.."(yes Hermione, how did you know so much about Harry?)
Hermione:"..Friendship, Courage and - Oh Harry!" (friendship, courage and what? family?)

Chapter one: Dumbledore has just said that he was going to leave Harry with the Dursleys. At first McGonagall doesn't agree:
Professor McGonagall opened her mouth, then shut it, then changed her mind and swallowed and said "Yes - yes, you're right, of course"
Here J.K.R insists alot, doesn't she? (McGonagall opened her mouth, then shut it, then changed her mind and swallowed..) What was Minerva going to say?
Was it: "Don't you think he should be with his sister?"
Halloween in SS: Hermione cries, alone in the girls toilet. Let us see it from Hermione's point of view..that she is harry's sister. Lets see if her behavious is understandable. In the beginning of SS, she is finally going to meet her brother. She knows that Harry is famous, and she maybe even knows that Harry doesn't know anything about the wizarding world..so what does she do? She studies hard, so she can help Harry into the right trackin Hogwarts, to make his change in the wizarding world easier to handle. She goes on the train in track 9, 3 quarters, and as soon as possible get to meet Harry.. with the cover of helping Neville find his toad. She see's Ron with Harry, and maybe she's already jealous: Harry already had a friend! maybe he diddn't have to prioriatise and thrust her...maybe she wouldn't have to help him at all. So what does she do? She picks on Ron, twice. First with "Are you sure it's the right spell? Well, it doesn't seem to be any good." and "by the way, you have some dirt on your nose". By that point, Hermione maybe sees Ron as a threat to her and Harry's relationship. Then we come to that special halloween day. Hermione already feels down because it was excactly 10 years ago her real parents died. And even more, instead of being pared together with her brother, she got pared together with her rival. She tries to prove to Harry that she's more useful and better than Ron.. so once again she outshined Ron!
And it became too much for Ron and he says "She's(Hermione) really a nightmare!" to Harry. Hermione hears this and bumps into Harry, and starts crying. Let us look at it from this point of view:
It is 10 years ago her parents died, plus it seems like as if she's loosing her brother to Ron, if Harry wouldn't like her, who would she have left? He's the only real family member left, and she knows about it.
But in the end the same night, they became friends, excactly 10 years ago their parents died.
NOTE:J.K.R never made it so that Hermione got to look through the Mirror of Erised, like Harry and Ron did. Why? What would she have seen there? Would it have ment too much? In book 2 after Hermione and Penelope got attacked, prof. McGonagall goes straight to Harry and says:
"Potter, I think you should come with me", was it because Harry was Hermione's friend? If it was so, why diddn't McGonagall call Ron too?
But she doesn't seem to care about Ron..she includes him, after considerating, and just because Ron ran after them:
"Yes, I think you should come too Weasley"
Notice that she said "think". Quite weird isn't it?
It's fully understandable that Harry and Hermione are sibblings, and McGonagall knows it too.

And ahwile later in the second book prof. McGonagall started crying when Harry asked if he and Ron could go visit Hermione in the hospital wing:
"Yes Potter, of course you can visit Miss Granger (by this point she has to blow her nose).
Yet again..not a word about Ron!
And note that she's allowing Harry to break one of the saftey rules! Not like McGonagall right? It must've been under special circumstances that she acted like that. Maybe she thought:
"Poor boy! He doesn't know..He doesn't know, and still he must feel it somehow..and he misses her!" (it's at this point she has to blow her nose)

Clue 1. from PoA: Lupin's class with the boggart, everyone was allowed to meet the boggart, except Harry and Hermione.Lupin diddn't want Harry to do it because he thought (wrongly) that Voldemort might come up. But why diddn't Hermione get to? that was never answered.
A boggart can give lots of clues, like Lupin's boggart(a full moon), that reaveled his big secret. So this could mean that either Lupin diddnt want her to meet the boggart because of personal reasons, or Dumbledore diddin't allow him to let Hermione meet the boggart or maybe Hermione diddn't want to meet the boggart infront of all these people and stayed behind after class to explain why she diddnt want to do it. And by the way, in the fith book, when Hermione meet the boggart in one of the OWL tests, she said that McGonagall told her that she "failed everything". Did "everything" mean her exams only? Quite silly right? I think her boggart actually said she failed everything: Hermione saw a dead Harry and a mad McGonagall telling her that she failed in protecting Harry!

Hermione's original name was Hermione Jane Puckle, but J.K.R changed it for some reason to Granger, but i think i know why, Hermione Jane Puckle, Harry James Potter, H.J.P on both!! So i think J.K.R changed her lastname was because she didn't want it to be obvious