IIRC I think it was mentioned or implied in "Day One" that that Butters had been sparring with the Einherjahren as part of his training regimen with Michael.

Well, he may just haven't had the chance yet, he has been a very busy little man after all.

I am not sure what point you are trying to make here...in any case I think all this shows is the danger in having the wrong person in the role of Warden, and so supports the idea it is better to have no Warden than a bad one.

That is called taking the easy way out, and it is dangerous.  A better solution would be to be very careful as to whom you put up to be Warden. 

I get what you're saying, but the entire Dresden Files series (not graphic novels so much or side stories of other characters) are meant to be Harry's journals. This much has been implied since Storm Front. Harry makes constant general statements through out the series. The very scene you reference is a massive nod to the fact that the series that we readers are reading are Harry's journals.

But the subject in question is Eb's journal, not the overview of Harry's journals.  We don't even know if Harry wrote his files contemporaneously as they happened or as an end of career over view of what happened in his life. 

And that particular passage that Ebenezar wrote is deduced by Harry as being left for him to read. Ebenezar wanted Harry to a) think about what the Island might actually be b) let Harry know the Council is taking special interest (in a negative way) in him and c) that Harry has Ebenezar's support (despite the hint about Maggie).

It really makes no difference whether Eb meant for Harry to read it or not, it is still Eb's own personal view of the situation.  Eb says,

I sometimes can't help but think that there is such a thing as fate-

Notice he says "I" not "we" nor "the Council thinks."  In my opinion it makes it his personal view, not a general view taken up by the Council.

Harry claimed the Island to give him a tactical advantage against a confrontation between him and the Skinwalker, the White Council and the White Court, and whichever Black Council operatives showed up to fight (including the mole in the Council i.e. Peabody). Harry had no idea the amount of tactical advantage the Island gave otherwise he would have won the battle far quicker and easier. He also had no idea the strategic value or the danger of the Island. He might have not rushed into it so quick otherwise.

Admittedly Harry didn't think it through, he surmised and was right that the island if he was successful would let him know where his attackers were coming from.  But that is all he got, since he had no clue of all the implications of what he had done, he was continued to fight the battle with a pea shooter when in effect he had a nuclear arsenal at his disposal.. It is a lot different now, that he understands.  One more point about the importance of the island having a Warden building on what Morriswalters says in the next post about the island having a two year old in charge [i.e. Alfred]

Here is what Morgan said about an intellectus, which Alfred/Demonreach/Island is; page 279 Turn Coat

"And since beings of intellectus so rarely understand broader ideas of cause and effect, they can be unlikely to realize that a given event might be an indicator of an upcoming assassination attempt." He turned to me. "Though that's a terrible metaphor, Dresden.  Most beings like that are immortal. They'd be hard-pressed to notice bullets, much less be threatened by them."

The above is the crux as to why the island needs a Warden, though well equipped to defend itself, including the prison, it has a hard time recognizing when it is threatened.   

I think you're going too specific there, in regards to what the Council are thwarting. I see it more as Ebenezar saying that the Council are getting in their own way and if they just let their real allies like Harry help them they might actually achieve some good, but it's their internal machinations and one-eyed behaviour that make it so much harder on themselves. I say this as Ebenezar refers to this "higher power" arranging "events in [their] favor" rather than pointing out specifically that a higher power seems to want a Wizard in the role in contrary to the supposed views of the White Council. But perhaps we will have to agree to disagree here though. I do believe that the "higher powers" i.e. Heaven do seem to play 4D Chess, and Harry is one such piece. It is hard to really see "luck" in the Dresdenverse considering some of the powers that are involved. It might not be as direct as the Knights, but things do seem to be arranged that should Harry make certain choices things put the good guys in a better position. But for Heaven to actually place someone in a position, they run the risk of abrogating choice, which seems to be directly counter to their mission. It all comes down to what choices people make.

Oh I agree that the Higher Powers are playing four dimensional chess, and Harry indeed is one of the pieces.   If Harry were a mere pawn, I would agree that that would abrogate choice, but Harry has never been anyone's pawn.  Actually in his flexibly, he appears to play more like a Rook, very useful dangerous piece with plenty of choices of movement.

Well, to be honest I think the Senior Council (in particular the Gatekeeper and the Merlin) are quite aware of some of the worst things in that prison. Which explains at least the Merlin's reaction. We don't know what the Gatekeeper said. Mab said Harry could do it...not that it would easy or even well controlled. We don't know the risks. I suspect that the battle of will would be intense, particularly the more powerful the being. The consequences of losing might be lethal, and not just to Dresden. We don't know how far a prisoner could go from the island, or how much control they would have outside the Island. Harry acknowledges that he could compel Ethniu but qualifies it that it would be "tricky and treacherous as hell" and "massively, massively unwise". We don't know what Kemmler did or didn't do while as Warden, although we do know he had powerful spirit allies too. The main thing that might have stopped Kemmler was that he knew the risks of trying to control a dark god or something and didn't think it might work out for him, not to mention that he spent only a little time on the Island as the Council worked very hard to prevent him from returning there after a while. Jim said the Council prevented him, hence why Luccio was in the Wild West in a Fistful of Warlocks (among other things). Do you really think Demonreach would stop a Warden using inmates to their advantage? I don't think Demonreach has a concept of morality. I think it only cares about the security of it's inmates, and putting more monsters in it's cells.

But that is why the mantel of Warden is so dangerous, that leaves open the question, why hasn't a Warden done it before now?  Kemmler may have known the risks, but why would that stop such a dark wizard?  I don't think the fail safes built in have anything to do with morality, more of practicality.  Why establish a maximum security prison, if the Warden could let any one out for his own use and become just another monster?

One more thing, it may be a matter of Fae semantics verses mere mortals, but when Mab said that Harry could use Ethinu to do his bidding, she wasn't exactly right but nor was she totally wrong.  The Ley lines that run under the island come from the prison itself, the energy of them is what the monster/inmates are giving off.  In Turn Coat while Rashid warns Harry against tapping into their energy, he also says;
page 299

"First," he said, "do not tap into the power of this place's well.You are years away from being able to handle such a thing without being altered by it."

I take that to mean that while Harry isn't ready for it now, in the future he will have the knowledge and the strength to tap into the well without changing himself.  Is that what the Council is afraid of? That Harry will tap into the Ley Lines before he is ready and turn into a monster?

Possibly.  It certainly was created at several times at the same time.

I basing this on when Harry and Bob visited the island in Cold Days, Harry learns about the attack. He is told it is coming the next day but then Alfred with Bob's help start in that it may have already happened etc.. So if that is possible, then Harry knowing what that he was going to name the island Demonreach a thousand years ago is totally possible in my opinion.

With Bourbon as expensive as what I was drinking I don't expect a headache.

You should get something for your money...   However the redeeming bit about something of that quality it isn't for swilling, it is for sipping and savoring in small quantities, hence no headache..

I'm sitting at my desk drinking a really good Small Batch Bourbon and listening to some of my favorite music and had a melancholy thought. Was Mab's order to Harry a foreshadowing?  Will Harry have to kill Molly?  Worse yet, if true, who will Molly kill before Harry can stop her? I can't really say there is any one thing that is the genesis of this thought, but it does follow the general theme that Butcher has always presented.  How can I torture Harry?

Since I'm shipping Harry and Mab, in my minds eye I see Harry holding a dying Mab in his arms as the stars go black in the sky.

You should know better, never mix bourbon with The Dresden Files, it will give you a bad headache every time...

My reading of that passage in Eb's diary is a bit different to yours. I read it as Ebenezar generalising about how fate or God seems to be on the White Council's side, despite the fact that the White Council keeps making mistakes that make it harder for God/fate to help them (due to their ignorance of the ineffable plan of God/fate). I don't think he is being specific about the White Council being ignorant of Demonreach - otherwise why would the Merlin react so strongly (along with the rest of the Senior Council)?

It is just a personal opinion, but I don't think Eb would make a "general" statement opinion in a personal journal.  A private journal is meant to be just that, in other words, what his real personal opinion is, not meant for public access.  So what does he say?

. . .seems clear that he had no idea of the island's original purpose.
I sometimes can't help but think that there is such a thing as fate--or at least a
higher power of some sort attempting to arrange events in our favor despite everything
we, in our ignorance, do to thwart it.

If you look at the first line of that paragraph, Eb is implying and it is true, that Harry stumbled into becoming Warden of the island.  Harry no clue that the job even existed or that the prison existed, he was just desperate to come up with a way to defend Morgan from unjust treatment from the Senior Council and it was the only way his power could match theirs. 

Then he talks about "fate" and guidance from a "higher power," in spite of some of the moves of the Council to thwart out of ignorance.  So just what is the Council thwarting?  Returning to the subject of the entry in the journal, the installation of a Warden for the island.  Clearly because without a proper Warden as we see later in Cold Days and confirmed by Harry in the first chapter of Skin Game, the island is vulnerable.  So you can say it was mere luck that Harry did what he did and became unwittingly Warden at a critical time.. Or fate and guidance that it was Harry who did this and not someone more corruptible for lack of a better word who got the job at this critical time .

Which gets us to the "ignorance" part of that statement.  We know the Council isn't stupid, but at the same time they fear the island having a proper Warden so much that they'd rather risk it being successfully attacked than have one.  Why? For starters if the Council at this point knew half of the "weapons" Harry has at his disposal they'd freak out more than they already have.  But is that fear real?  Consider what Mab told Harry in Battle Ground, that the prisoners were now his to control.  If he wanted to use Ethniu to attack someone, he could make her do it.  Now that would be very bad for the Council.  But is she right?  Mab can be mistaken, there must be some unwritten fail safes built in to prevent that.  Why do I say that?  If Kemmler was half as bad as they say he was, why didn't he do that very thing while he was Warden?  What stopped him?  Did Alfred or something else boot him off the island?  In another thread someone said that Jim said he tried to get back to the island, but was prevented.. By the Council or the island itself?  That is an important question.  So by ignorance, I think Eb meant that the Council fears anyone who might control the prison because they are indeed ignorant of the fail safes that prevent the misuse of the inmates of the island's prison. 

Then he says;

    The Merlin has demanded that we put the boy under surveillance at once.I think he is a damn fool.

Eb knows Harry a lot better than the Merlin does, he also loves him, he is his grandson.  Eb doesn't think that Harry will turn into a monster just because he is now Warden of the island.  Then he says he trusts Harry, but then adds as an aside that he also trusted Margaret, which is an admission that he sometimes makes mistakes in judgement. 

  Oh why don't they go all out and do Lord of the Rings?

The unnamed prisoner says that "He belongs to be here" (paraphrasing). I wonder if Thomas will adopt this same attitude after talking with him or once he gets off the Island that he will feel that he belongs back in prison.

He might, he was troubled before, that is why when he went to live with Harry he starved himself because he knows on some level it is wrong to feed on other people.  Then he found some peace in nibbling on people, bringing them pleasure while feeding his needs.  Then after the Skinwalker got done with him, he once again saw humans as kine.  Not saying that he fed until death more people since Turn Coat, but he now he has to face the harm that he has done.  If he cannot rid himself of his Hunger Demon, he may also come to believe that he belongs where he is at.