Could someone explain to me the blood wards of 4 Privet Drive?

Question

We know that Harry spends 10 months a year in Hogwarts and only 2 months (or less, as the time spent in No. 4 seems to decrease with every book) at Number 4. We are told that Dumbledore himself made the blood wards and that they are apparently based on Lily's love-power protection from '81, and are recharged by Harry's proximity to his relatives. They can apparently recharge in a month or so and then last for about a year.

But what are the actual benefits of the wards for Harry?

Do the wards recharge Lily's protection? Is it the other way around?

Where does the power that recharges these wards comes from? Harry's blood relatives Petunia and Dudley are a) 100% muggles b) most certainly don't Love Harry.

So what do these wards DO actually? What is their purpose? What do they stop?

They don't stop magical creatures (Dobby, various owls), they don't stop magic users (Order, Sirius in his dog form), they most certainly don't stop those with bad intentions towards Harry (even if Petunia and Dudley are part of the wards, Vernon isn't related to Harry and he abuses him to a ridiculous extent), they don't stop anyone from sending him (potentially booby-trapped) letters/parcels. They don't hide the location from anyone (the Ministry sends him letters with the precise address)

If they protect from Death Eaters then why are Order guards even necessary?

If they protect from Voldemort then WHY does Harry returns after V's resurrection (and ability to touch him without burning to crisp)?

What is their range? Only the house? The whole property? It can't be any further than that because Dementors chased Harry and Dudley around the neighborhood.

Are these blood wards more than just a plot device?

Answer 1

Order of the Phoenix, Chapter 37 has this (as @user1129682 noted) discussion between Harry and Dumbledore.

‘She doesn’t love me,’ said Harry at once. ‘She doesn’t give a damn –’

‘But she took you,’ Dumbledore cut across him. ‘She may have taken you grudgingly, furiously, unwillingly, bitterly, yet still she took you, and in doing so, she sealed the charm I placed upon you. Your mother’s sacrifice made the bond of blood the strongest shield I could give you.’

‘I still don’t –’

‘While you can still call home the place where your mother’s blood dwells, there you cannot be touched or harmed by Voldemort. He shed her blood, but it lives on in you and her sister. Her blood became your refuge. You need return there only once a year, but as long as you can still call it home, whilst you are there he cannot hurt you. Your aunt knows this. I explained what I had done in the letter I left, with you, on her doorstep. She knows that allowing you houseroom may well have kept you alive for the past fifteen years.’

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So, to answer your questions:

• But what are the actual benefits of the wards for Harry?

  See the next question.

• So what do these wards DO actually? What is their purpose? What do they stop?

  There seem to be 2 related ones:

  1. Direct protection from Voldemort's attack:

     whilst you are there [ Privet drive] he cannot hurt you.

  2. Protection against assorted Dark wizards and possibly creatures. See Harry's note to Dursleys in Ch3 of Deathly Hallows:

     ‘I hope so,’ said Harry, ‘because once I’m seventeen, all of them – Death Eaters, Dementors, maybe even Inferi, which means dead bodies enchanted by a Dark wizard – will be able to find you and will certainly attack you. And if you remember the last time you tried to outrun wizards, I think you’ll agree you need help.’

• Do the wards recharge Lily's protection? Is it the other way around?

  The wards are not related to Lily's protection.

  Lily's protection was what made Voldemort personally unable to touch Harry. See PS with Quirrell. THAT protection expired in the end of GoF when Voldemort used Harry's blood to get a new body for himself!

  See the full discussion on the differences between the two here: " Why did Lily's enchantments work for Voldemort? "

• Where does the power that recharges these wards comes from? Harry's blood relatives Petunia and Dudley are a) 100% muggles b) most certainly don't Love Harry.

  The wards don't seem to need to be "charged", merely "activated" (or "sealed" using Dumbledore's wording). But aside from that one comment, there's not much other detail in canon, so you can interpret it otherwise.

• They don't stop magical creatures (Dobby, various owls)

  Correct. House elves use different magic from wizards. Matter of fact, I'm pretty sure a house-elf could have been ordered to off Harry and have a chance to succeed. They DO seem likely to stop Dark creatures based on above Harry's quote from DH7.

• They don't stop magic users (Order, Sirius in his dog form),

  Actually, Sirius/dog was never in the house, just around. The Order was designed to be allowed to be ignored by the charms/wards, presumably (no explicit canon support but they WERE able to enter the house, in HP1, HP2 (Weasles) and HP7, at least.

• they most certainly don't stop those with bad intentions towards Harry (even if Petunia and Dudley are part of the wards, Vernon isn't related to Harry and he abuses him to a ridiculous extent)

  Correct. The wards are there to protect from Death Eaters. Not to protect Harry from any harm at all.

• they don't stop anyone from sending him (potentially booby-trapped) letters/parcels.

  I have never seen any mention in canon of that being either true or false. The only mail Harry gets is from either the Ministry or friends/Order.

• They don't hide the location from anyone (ministry sends him letters with precise address)

  They do hide the exact location (but not the whereabouts - see Moody's quote in Ch4 of Hp7), but not the publicly available address. We know that owls can find people who are hiding, e.g. Sirius in his cave.

• If they protect from Death Eaters then why are Order guards even necessary?

  First, there were no "Order guards" as a rule aside from Squib Mrs. Figgs and once in a while, random patrol in the neighbourhood. Remember that it's the house that's protected, not random surroundings.

• If they protect from Voldemort then WHY does Harry returns after V's resurrection (and ability to touch him without burning to crisp)?

  Because that's the whole point of Dumbledore's charm. It's built around Lily's protective magic, but is separate from it, and therefore isn't broken by V's using Harry's blood.

• What is their range? Only house. Whole property? It can't be any further than that because Dementors chased Harry and Dudley around the neighborhood.

  Only the house. Moody says in Ch4 of Deathly Hallows:

  ‘[…] They might not be able to get at you or this house while your mother’s charm holds, but it’s about to break and they know the rough position of the place. […]’

So far the 'all powerful blood wards' seems like nothing more but a plot device.

Answer 2

It is not the time spent at Number4, it's the fact that, even though spending most time at boarding school, Harry calls that place, where his mother's blood flows home. (roughly transcripted from ... HP5, Ch37, I believe). That fact is what keeps Lily's protection alive and Harry safe from Voldemort.

Apart from that. I suppose it's school rules and policies that pupils return to their families for the summer.

Answer 3

" ' - If they protect from Death Eaters then why are Order guards even necessary?'

First, there were no "Order guards" as a rule aside from Squib Mrs. Figgs and once in a while, random patrol in the neighbourhood. Remember that it's the house that's protected, not random surroundings."

In Book 5 there are Order Guards, we know Mudungus Fletcher was supposed to be guarding the house when the Dementors came, and he was doing it close enough that Harry could hear and recognize the sound of apparation he made when he left early. I think the Guards were there because the wards only extended to the house. After the Dementor attack, the letters all tell him to 'stay in the house' so the Guard was there in case he ever left the house. Which is ethically, unusual. Basically a bunch of adults that he barely knew or didn't know were part of a conspiracy to keep him under house arrest in a place he was abused. Furthermore, if the Death Eaters knew the general location of the house, they could have nabbed him when he was a child, since he had to leave the house for public school, so Dumbledore's protections were basically useless for about a quarter to a third of every day. It's possible that it just never occurred to him that muggle families send their children to school before 11, or are even required to do so by law. Dumbledore is a halfboold raised in a magical home, so he likely wouldn't have gone to primary/elementary school as a child and might never think others could.

And whenever Harry thinks of Privet Drive, the word 'home' is never used, except by others. However, Petunia did make it his home by taking him in, so until he thought or said the words 'not my home' specifically about Privet Drive, the protections should hold. They were sealed by it becoming his home when he was too young to understand the concept, so couldn't dispute it, and they would hold as long as he never disclaimed it directly. Or at least, that is what I and a lot of others, usually fanfiction writers and readers, have come to understand the idea. Which fits the above comment about the "vague and specific" nature of the magic. A lot of us have wondered about the 'hole' in the Blood Wards created by Voldemort taking Harry's blood. Some think that is why the fifth book has guards for Harry while he is there, when that was never a thing before. I have never realized that Dumbledore's wards on the house are actually separate form the ward on Harry. That is actually an interesting point, and I so plan to hunt that page down in the books and reread it.

Answer 4

The way I see it, the blood wards around the house are either fake — I can completely believe this because Dumbledore is actually rather manipulative — or a plot device filled with holes.

A lot doesn't add up about them. Dumbledore claims they exist as long as the place is considered home to Harry. The thing is, magic is clearly both vague and specific in the books. For instance, Snape owed a life debt to James Potter but the terms of it are never specified, thus why Snape fulfills it through guarding Harry. At the same time, it can be very specific, such as with dark magic (e.g. You have to have the will and feelings to cast any of the unforgivable; you can't just feel hatred, you have to WANT that person to die, to be killed by your own hand). As such, I kind of figure that blood wards, something sound more like dark magic, would specific. It can't just be "this is my home", you have to want the place to be your home, to consider it emotionally as your home. The problem is that Harry has never considered Privet Drive his home. Anytime he speaks of it he calls it "the Dursleys'", showing that he views it as the place he has to stay, a home for the Dursleys, but not a place he considers home.

Moreover, like you said, the wards give less than should be given. I mean honestly? The price for the wards are abuse, and the only thing the bloody wards do is keep Death Eaters out. The Death Eaters know the general area of where Harry lives. They are USELSSS. All it would take to kidnap Harry is to ambush him when he goes to the station for school. He'd be much safer at Grimmauld.

The price? Harry is abused by his aunt and uncle and Dudley is allowed to harshly bully him. The Durselys emotionally and physically abuse him. He's rarely called by his name, his parents are constantly insulted, and treated worse than a house elf. BOTH his relatives abuse him. How Venron does it is obvious. Petunia mostly does it emotionally, but a few times she does so physically. For instance, there is a scene where she attempts to hit Harry with a frying pan. The wards are not worth it! He'd probably be treated better by Death Eaters while he lives in a cell.

Overall, this seems to be a mixture of a plot device and glossing over. Rowling constantly glosses over controversially dark things. It's obvious that Harry is abused by it is played off as the Durselys just being mean. Technically, Harry should suffer emotionally and physically from the abuse, but all of it just plays him off as being a lonely orphan. I suppose it's because of the contrast between Harry and Tom: two similar boys with similar backgrounds. I think Rowling is trying to portray Harry as the boy who overcame his bad childhood while Tom let his consume him. If anything, Tom's reaction to his circumstances is far more realistic than Harry's.

Because of all of this, it is impossible, by the terms set, that the wards should even work and this is probably just a result of Rowlings several glossing overs. Harry is abused, but showing that too clearly means he won't consider the place home and this they won't work, so let's change his reaction to something less drastic so they do work. It's just a poorly written plot device.

It's also probably one of those things Rowling decided she wanted but didn't think through. For instance, she wanted Ron and Hermione together because of a petty reason, even though those two would realistically never be able to have a long lasting relationship without being at each other's throats. This kind of reeks of 'I want Harry here but I need to have a good reason' but her reason ends up halted baked because it logically makes no sense for Harry to live there. And honestly? Harry's father was a pureblood, which means Harry is related to several PUREBLOOD and possibly halfblood families. It's BS to put him there because "the Durselys are his only family". There's no good reason to have him there, making this a poor plot device, used just to give Harry some good background, but made poorly because none of the possible interesting character traits are used because it could seem controversial.