Petunia told the children about the new wards as soon as they returned from school. She also told them about the conversation concerning their magic.
Harry frowned. "How do they know?"
Petunia had no idea. "It could be the same way they find out about married couples or the illegal use of magic. As long as the details are unknown and so are the names, the rest is not as important."
The children nodded. Harry had some more to ask. "Are you sure the new wards won't stop us? I don't want Hermione to be tossed to the channel, you know."
"They won't toss you if you try to apparate out of here. They will either let you through or not at all. You may try when ready."
Petunia wasn't ready for Harry to just disappear immediately, reappearing a few seconds later. "We can easily go out and back. Hermione is going to check this soon. She wants to wear only a swimsuit, just in case she's not accepted. I'll go wait in my room."
Petunia could only shake her head in wonderment. Her family had changed drastically since accepting Harry, and she felt it was all for the best. Without Harry, Dudley would have stayed a subpar pupil and a bully. She doubted he could achieve much in life in that case. Since accepting Harry, he brought a lot of changes. Dudley had become one of the best pupils in his class, although she thought Hermione had just as much to do with that as Harry. Dudley also grew more responsible and no longer had a tendency to bully.
It also changed Vernon, forcing him to accept things he couldn't understand and not put every such thing under the title of 'Freakishness', as he had used to do earlier in life.
She felt that she also gained from it. Despite being unable to bear another child, she was now the mother of two very good children who were quite different from each other despite some common interests. It felt good to say, 'These two are my children.'
–..–
Just like Harry, Hermione found no problem in using their mode of apparition to come and go. Harry told her about the updated wards, of course. Petunia was sure that the girl, and possibly the boys too, would try to find and learn all they could about wards in the near future. Unless some more urgent or interesting topic distracted them, of course. She didn't know they were already studying wards.
Indeed, that weekend, Hermione presented three books to them. "I checked some more, but these books cover the same topics with more details. I think we should start with the theory. It would make the specific wards more understandable, I believe."
This was no different from other topics they'd studied, although the books looked much thicker. Still, just from the table of contents, it was clear that they didn't need to read it all before trying the more specific books.
Harry was most interested in the ways to analyse wards and find out what they did and how. It was a mixture of theory and practice that he found very intriguing. Unfortunately, it also contained some elements of Runes and Arithmancy, but both he and Hermione only considered it a challenge, not an obstacle. Dudley was more of the 'hands-on' type of person and was more interested in specific ways to check wards or to erect and remove them. Theory was not so interesting to him, although he did well enough in learning it.
The children needed more than a month to feel confident enough to try and analyse the wards, or some of them, at least. It was a tedious task and would take more than one weekend, but they felt confident about their abilities and weren't deterred when something proved more difficult than anticipated. During the first weekend, they worked on that, they deciphered the anti-apparition ward and the additional ones deflecting other types of magical travel, along with the one protecting against fire and flood.
"Next time you come, I want to try to erect such wards on my house," Hermione stated. Both boys nodded.
Petunia, who heard them talk, was sure that they'd erect even stronger wards. She could also see their halos growing stronger and wider as time passed. It was fascinating and frightening. Their halos were already about the same as Dumbledore's, and she was sure they would grow stronger and wider even before reaching Hogwarts. She had no idea what it would mean for them.
–..–
It took some trial and error to erect the wards on the Granger house. Some of them, at least. The children encountered no difficulty in erecting the fire and flood wards and even added a structural ward to protect against earthquakes or bombing. They considered this quite simple, and they would even become redundant after erecting the more complex wards, but these wards were more like a 'proof of concept' for them, although they didn't know that saying.
"Now that we're sure we can erect such wards, we can try the anti-magical-travel wards. Once they work, they won't send anybody into the English Channel, but they'd land about a half-hour walk from here in the same direction they came from. When we check them, we should be ready to apparate again, in case we land on a highway or a lake or anywhere else that can be dangerous." Hermione already had her instructions ready.
"But how can we check? Our way of magically moving is not quite apparition, and we know nothing about house-elf popping or about phoenix travel," Harry asked.
Hermione smiled. "I copied the methods from the wards where you live. We all tried to understand them, and we found out how they work. We then thought about how our method differs. I just added this to the ward. I'll key us all in after testing, but not immediately. We need to check the wards first, you know."
Both boys smiled. "Let's do it now!"
The first time, the ward stopped thrown pebbles and also one running in with a drawn knife, but fell short of stopping them from apparating in or out. The second try worked slightly better, but only threw the unwelcome guests a few paces away. That wasn't good enough.
The three concentrated, adding the parts planned for each and enhancing each other's magic. This time, it worked as expected, although they needed to apparate back to a hidden place in the nearest park before they could discuss their success.
Hermione then added herself and Harry to the wards and checked again. They could apparate in and out, but Dudley couldn't. She then added him, too, and it all worked as planned.
"We should next add the ward against the killing curse," Harry noted. "We first need to learn how to make the magic in the ward conjure objects, or it won't work."
Hermione already had a plan. "We can already erect the shield ward, though. It should protect what's inside from any spell that can be shielded against. If we tie it to the ground well enough, it could probably withstand even many powerful spells, powering itself from the magic in Earth."
Harry frowned. "Have you found a ley line under your house or some other source of magic?"
Hermione shook her head. "No, but the whole Earth has magic. If we sink the ends of the wards deep enough into it, they'd be permanently powered by Earth's magic. We've already done that with the other wards we've set. Didn't you notice?"
Dudley answered this time. "I thought it was just like digging deeply for the foundations of tall buildings, for better stability."
Hermione smiled. "It may add stability to the wards, too, but they don't quite need it since it's Magic, not Physics." Her expression turned mischievous. "Would you like to try and overpower them with our combined magic?"
Harry shook his head. "We've put quite a lot of our magic in the wards. I doubt we can use as much magic now. Maybe another day, when we're not magically exhausted."
Hermione frowned. "Do you feel exhausted now?"
He smiled back. "Not quite exhausted but less powerful than before erecting the wards. I could probably erect a few more wards, but I doubt I could overload any. We need much more power for that."
Hermione smiled with relief. "Then, I have an idea for another ward. We can discuss it and then try to erect it too."
Dudley got interested. "What kind of ward?"
"A hiding ward. If we set it correctly, it should hide what's under it from whoever has bad intentions for the place or its occupants. We can tie it to the other intent-based wards or make it independent. We also need to think about what it should show when hiding something."
Harry gave it some thought. "It should probably show the place as if abandoned, ruined or vacant. Like the plot is not yet built, or the house has been demolished to make room for a newer one. The illusion should work day and night and even reflect light and make shadows like it was real, I think."
The three started discussing what they thought would work and how to achieve it. Hermione referred to the books more than once, of course. She had found no such ward in the books, but there were illusion charms and invisibility charms in abundance. The three children found the idea interesting enough to do some research in the books, but eventually reached the common conclusion: it was simpler than the other wards if erected with the right approach.
It was then a child's play to erect it. Unfortunately, they didn't know how to test it, but that didn't matter. They trusted the other wards to act even if this one failed.
When the boys returned to the Dursley house, they were a little tired, but thought they could still upgrade their wards. Harry and Dudley held hands and added the hiding ward. The rest didn't matter much. They trusted the goblin wards and only added theirs as an additional layer for extra safety.
–..–
Harry made it a habit to cover his forehead with his long hair whenever he had a magical adult visiting. He was actually content not to need to hide his scar, but he didn't want them to be aware of having it removed either. He wasn't sure they would all like the news.
Dumbledore came for a visit shortly after the New Year. Both Harry and Dudley acted as usual, not mentioning anything magical. When asked specifically, Dudley only mentioned trying to consciously replicate the ball incident.
"I tried to recall what I felt at the time and what I thought to cause a thrown ball to change direction," he explained.
"And how did that go?" Dumbledore showed interest.
"Very badly, at first. Then Harry and Hermione encouraged me, and after many failed attempts, I finally managed to do that, somewhat."
"That's a remarkable achievement, you should know. Very few adult wizards can do such things. I'm not even sure I can do it. Not without quite a bit of training, for sure."
Dumbledore gave it some thought. "Anything else?"
Dudley smiled. "Once I understood how to do that, I taught both Harry and Hermione. They can do it now as well as I can."
Harry wasn't sure Dumbledore liked the idea, but the old man masked his surprise too quickly for Harry to discern his feelings from his expression. He had a feeling Dumbledore didn't like them becoming so proficient, and, Harry felt quite sure about it, envied the children for their abilities. He subtly made Dudley understand that he had said too much.
Dudley also noticed Dumbledore's reaction, so he added, "We still fail most of the time, but we succeed occasionally. We hope to succeed more often as we grow older."
Judging by the fleeting expression on the old face, this was the right thing to say.
Yet Harry's (lack of) scar couldn't stay a secret for long. During that same visit, the phone rang. Petunia answered and then called, "Harry! It's for you."
Harry turned his head quickly, making his bangs fly aside and exposing his blemish-free forehead for a second. He could hear Dumbledore's gasp of surprise, but there was nothing he could do about it. He talked with one of his school friends who had something to ask but paid most of his attention to the conversation his aunt had with the old man.
"What happened to his scar? I thought there was no way to heal it." Dumbledore didn't sound pleased at all.
Petunia was quite a quick thinker, and she had her answer ready. It was practically the truth anyway. "I understood that you knew of no way to heal it, so it was probably true of your healers, too, or you would have known of a way, even if not the details. Yet that scar bothered me since you left Harry with us. I then tried to think of other ways to heal it, finally realising that there were other magical species. It became even more evident after the children visited Diagon Alley. I thought that the goblins might know of a way, unknown to wizards."
Dumbledore grimaced at that, but Petunia continued talking.
"I took Harry to Gringotts and asked for the healers to check him. They found something that prevented his scar from healing and removed it, allowing it to heal as expected."
Dumbledore sighed, sounding defeated. "I was unaware of them having such good healers. It looks like wizard-folk ignore their abilities more than is justifiable. Do you know what they took out of there and how?"
Petunia shook her head. "All I know is that it was a lengthy ritual. I was not allowed in, as you may expect, and Harry was put to sleep. It was to prevent him from moving during the ritual and prevent any pain, in case the ritual caused any. They said they captured that entity in a crystal to be first studied and then destroyed. I know no more."
Dumbledore gave it some consideration, sighed some more, and then smiled hesitantly. "It's good for Harry not to have that scar any longer. I'm not sure what it may mean in the long run, though. I'll have to think some more about all the implications."