1. I think it was partly for the readers' benefits, so that we know what's going on. But it may also be because Aslan wants the Witch to clearly lay out her claim and to make her 'argue' for it in a way.

2. Umm. He may've used a rebuking or stern tone to help Edmund realise what he'd done, if he didn't fully realise before, and then a calmer or comforting tone to assure him of forgiveness?

3. Edmund knew he could trust Aslan, and that he no longer had to fear the Witch.

4. I have absolutely no idea.

5. If the Witch could claim anyone, she would; they would all live under her fear and Aslan would have no claim against her. But traitors have broken the law and thus there is a price to pay.

6. He's a traitor against his siblings, for one thing; he betrayed them. For another, he didn't have to meet Aslan to work against him, which was what he was doing. I think it kind of expands his character by placing him and his actions as part of something larger than just a simple sibling squabble.

7.

"Fool," said the Witch with a savage smile that was almost a snarl, "do you really think your master can rob me of my rights by mere force? He knows the Deep Magic better than that. He knows that unless I have blood as the Law says all Narnia will be overturned and perish in fire and water."
"It is very true," said Aslan, "I do not deny it."
"Oh, Aslan!" whispered Susan in the Lion's ear, "can't we–I mean, you won't, will you? Can't we do something about the Deep Magic? Isn't there something you can work against it?"
"Work against the Emperor's Magic?" said Aslan, turning to her with something like a frown on his face. And nobody ever made that suggestion to him again.

This part came up in Bible Study the other day when we were talking about why God's justice had to be fulfilled; I like how Lewis, very simply, discards the idea of not fulfilling the Law here.

1. Why do you think Aslan had the witch tell him about the Deep Magic?
For one thing so the Narnian's could her it. They seemed ignorant of it. It also highlights what the witch knows, which sets the stage to show what she doesn't.

2. What do you think Aslan said to Edmund? (If you don't want to guess, what tone(s) do you think Aslan used with him?)
I suspect he was fir at first and then gentle and forgiving. I suspect he asked Edmund questions and helped him to see where he had gone wrong.
3. Why do you think Edmund was so calm when the White Witch came to speak to Aslan?
He finally has his priorities straight and is focused on Aslan.
4. Lewis hints at some other powers that the witch might have, other than turning people to stone and keeping everything in a perpetual winter. What powers do you think these might be? Why are they important to her character?
She can make things look different then they are. She has the power to kill traitors; in fact, she has the right to do so. Without that power / right she likely would not dare to talk to Aslan.
5. Why does the witch only claim the rights to the lives of traitors?
It was all she needed to claim the right of.
6. How is Edmund a traitor, even though he had never yet met Aslan? How does this expand his character?
On a simple level he was a traitor to his siblings. It could even be argued that he was a traitor to the witch since he was then on Aslan's side. I think anyone not on Aslan's side could be seen as a traitor.

1. Why do you think Aslan had the witch tell him about the Deep Magic?
I like Valia and Twig's ideas that it's a combination of her being forced to justify her claim, and to expose exactly what her understanding of the Deep Magic is. However, I think it may have been for the sake of the children, as well, so they can understand why Aslan would even tolerate any idea of giving the Witch what she wants. Perhaps it was even in anticipation of what Valia quoted, the part where Susan wanted Aslan to work against the Deep Magic--he wanted them to understand why he could not and would not do such a thing.

2. What do you think Aslan said to Edmund? (If you don't want to guess, what tone(s) do you think Aslan used with him?)
I imagine the words "what's done is done" (or the equivalent" were used, but other than that I refuse to guess. I've always imagined his tone being rather similar to the conversation he had with --essentially, stating the facts as they are, that Edmund did, indeed, do some terrible things. However, I see his tone as stern, but gentle; I think by that point Edmund was already sorry for what he'd done and humbled, and I think he more needed to hear about forgiveness and that Aslan would set things to right.

3. Why do you think Edmund was so calm when the White Witch came to speak to Aslan?
At this point, Edmund knows that he has made a horrible, horrible mistake, and he likely knows that he deserves what the Witch is saying. There is literally nothing he can say or do to defend himself--except trust that Aslan will make things right, somehow. And I think Edmund already trusts that Aslan will.

4. Lewis hints at some other powers that the witch might have, other than turning people to stone and keeping everything in a perpetual winter. What powers do you think these might be? Why are they important to her character?

She has the power to kill traitors; in fact, she has the right to do so. Without that power / right she likely would not dare to talk to Aslan.

That's an excellent point; as Mr. Beaver says, it may even be how she convinced herself/others that she was the rightful ruler of Narnia. I wonder how she got this power, since (to my knowledge) it's never really addressed elsewhere.

One other thing I just recently thought about is that, especially in this book, we see two kinds of magic: a wild magic, which can't be tamed or wrapped up nicely in a box, which behaves as it will, but generally seems to work towards a greater good. There's the magic of the wardrobe (only leading to Narnia when those looking inside aren't actively looking for it, as well as possibly guiding the children into Narnia), as well as some of the power that we'll see Aslan use. Then there's the Witch's magic--very regimented, and while she's powerful and seems to have various different kinds of powers, it's all very specific. She uses a special potion to enchant Edmund, her wand is capable of either turning her to stone or illusion magic, but she's apparently not capable of simply blasting away her opposition. (I believe, had Aslan somehow been ambushed the same way she was, he wouldn't have lost a captive unless that was his intent). I think this is a factor of the Witch's magic not being natural, inherent, or given to her; it seems to be the product of studying the loopholes of the universe, the type of magic she has to fight for, one where she has to follow a specific set of rules.

5. Why does the witch only claim the rights to the lives of traitors?
I have a hard time believing that Aslan or the Emperor-beyond-the-Sea would give the Witch any more power than that--I'm a little surprised she earned as much as she did! But, as Valia said, traitors have already more or less forfeited their life. It's still an interesting question for how she earned the right to the lives of traitors.

Ironically... I wonder if the Witch would have had to actually give Edmund what she promised if he'd brought his siblings to her. Otherwise, wouldn't that mean she betrayed Edmund--and is therefore a traitor herself? I know, it's hard to enforce a system like that against yourself, but still....

6. How is Edmund a traitor, even though he had never yet met Aslan? How does this expand his character?
I agree that it's likely a case of Edmund being a traitor to his siblings. Also, if Aslan is responsible for the wardrobe bringing him to Narnia, then one might argue that he betrayed Aslan's intent for coming to Narnia by joining the Witch's side. It's hard for me to say his treachery was committed against Aslan or Narnia when he hadn't ever formally joined their cause.

1. Why do you think Aslan had the witch tell him about the Deep Magic?

Exposition for the children's and the army's sake (not to mention the reader's sake). It also puts both Aslan and the Witch on an even playing field. By both parties correctly understanding the rules it makes for less chance for trickery.

2. What do you think Aslan said to Edmund? (If you don't want to guess, what tone(s) do you think Aslan used with him?)

What would Aslan say to you?

3. Why do you think Edmund was so calm when the White Witch came to speak to Aslan?

I'm not sure he was entirely calm. The book says that "The only two people present who seemed to be quite at their ease were Aslan and the Witch herself." But "Edmund had got past thinking about himself after all he'd been through and after the talk he'd had that morning. He just went on looking at Aslan. It didn't seem to matter what the Witch said." Edmund felt like a different person than he was the day before, and indeed he was. I suppose it was somewhat like a former alcoholic who has been born again. After the chain is broken the addiction no longer has any effect and the temptation has no allure. Only one thing mattered to Edmund at that moment, and that was Aslan.

After it becomes clear that the Witch is after Edmund, he does have "a choking feeling" and is evidently nervous, but he puts his trust in Aslan and waits.

4. Lewis hints at some other powers that the witch might have, other than turning people to stone and keeping everything in a perpetual winter. What powers do you think these might be? Why are they important to her character?

She has enormous legitimate political power, in addition to the usurped political power we've heard about up until this point in the story. Due to her prodding around into Narnia's deep magic, she has discovered and legally attained the only position of power available to her: executioner. If blood is not spilled to repay treachery, it seems the automatic reaction built into Narnia's physics is disaster. The Witch uses this fact to her own ends, no doubt murdering the enemies that she can, and tempting the others that she can't, thus giving her a legal reason for execution. I doubt Edmund was the first to be fooled by the Witch this way.

Like the Deplorable Word of Charn, Jadis now wields the ultimate threat: the ability to destroy the entire world. None dare oppose her now...

5. Why does the witch only claim the rights to the lives of traitors?

That is the only authority that has been given to her. Although she can murder and go to battle against loyal citizens of Narnia, she cannot legitimately claim authority over them and everyone knows it. The only "lawful prey" that she has are the traitors.

In other words, there are two kingdoms at work here: The Kingdom of the Emperor Beyond the Sea, and the lesser Kingdom of Narnia. In the world or realm of Narnia, she had gained official status as "hangman" but in the country of Narnia she had no power until she used her status in the greater kingdom to usurp the monarchy in the lesser one. As Queen of Narnia she could kill any of her subjects. Since Edmund was not one of her subjects, she had to make him into a traitor and exert her executive powers over him that way, by the greater laws of the world. If he was not a subject of her country, then he had to be a prisoner of the realm.

6. How is Edmund a traitor, even though he had never yet met Aslan? How does this expand his character?

Good question.

My best guess is that it is because Edmund betrayed his family. Since his family (especially his older brother) had accepted Aslan's kingship, it might be argued that his betrayal of Peter was by extension a betrayal of Aslan, especially since Edmund had heard the prophesy about "Adam's flesh" sitting "in throne" over Narnia before he left the Beavers'. If he had thought about it at all on his cold walk to the Witch's house, then he knew that he was supposed to be King of Narnia under Peter and possibly under Aslan. But that wasn't enough. He wanted Aslan killed and he wanted to rule over Peter, not under him.

It is, of course, no secret that Edmund did not like Aslan from the first mention of his name, and sided with the Witch when it was clear that there were indeed sides to take. He not only chose to but wanted to tell the Witch about Aslan being in Narnia, and probably wanted Aslan to be turned into stone as well.

So Edmund's disdain for Aslan is quite clear, just as it is becoming clear that Peter is accepting Aslan's lordship, and regardless, Peter deserves Edmund's allegiance.

At least one definition of "traitor" given by Merriam-Webster is "a person who betrays a country or group of people by helping or supporting an enemy" and two definitions of the word "betray" are "to give information about (a person, group, country, etc.) to an enemy" and "to hurt (someone who trusts you, such as a friend or relative) by not giving help or by doing something morally wrong."

Edmund certainly hurts his trusting family by not giving help and by doing something morally wrong (trying to get revenge). He also gives information about a person, a group, and a country to Aslan's enemy, albeit not necessarily his own enemy if we are going by choice. It is clear, however, that the Witch is Peter's enemy, and it is also clear that Peter will "join forces" with Aslan. In conclusion, despite his conscience and better judgement, Edmund helps and supports the Queen, the enemy of Peter and the true Narnians (including the Beavers, his hosts) and of Aslan.

But does all of this explanation satisfy the original question: How is Edmund a traitor, even though he had never yet met Aslan? In other words, could he directly betray a person when he never chose to be on his side to begin with? But on the other hand, does one choose to belong to the nation one is born into?

Perhaps a better question is: Can someone be a traitor without knowing who's side they are supposed to be on?

It is clear from the prophesies that Edmund is destined to be Aslan's subject. Was that fact clear to Edmund as he was sneaking out the door while listening to the conversation? If it wasn't, does it matter?

As King not only of Narnia but of the world, didn't Edmund owe him his allegiance? Does not knowing Aslan was the King make a difference?

As a guest of the world, wouldn't it be called treason if Edmund tried to overthrow his host? Does not knowing Aslan was his host excuse him?

As a prince of Narnia isn't it treason to plot Aslan's destruction? Does not knowing he belonged to Aslan's kingdom make him no longer a traitor?

I think ultimately it comes down to the fact that Edmund is accountable as a traitor, because it isn't that he didn't believe that Aslan was the true king, but that he didn't want to believe that Aslan was the true king, but deep down, he did.