Nemesis seems to infect mortals and immortals alike, and will doesn't seem to be a part of it.
 Perhaps this argument could be made with a mortal; I'm not sure that it could be made to a being without free will.  Your statement seems to imply that Mab's will is that much stronger than Maeve's was, which is a fallacy - neither have free will.

Do you have any passages which can support Mab as infected?  Because I can think of a ton which imply that she isn't, including pretty much all of Cold Days.

Creatures without free will still have will. Vadderung, the Red King, and Mother Winter all demonstrate the ability to paralyze Harry with will alone (each time Harry gets progressively better at dealing with it - not at all, with help, and by himself). Mab absolutely has stronger will than Maeve. Also, Maeve didn't want to resist Nemesis. She wanted (the illusion) of free will and accepted it freely.

PG and CD both raise the issue of Mab being potentially infected. The story plays out in a way to demonstrate that Maeve was infected. My theory is that this could be misdirection from JB. We are meant to believe that only one of Maeve or Mab was infected when secretly they both are and the difference is that Maeve welcomes it and Mab resists.

Aneurysms are a problem in the circulatory system. They don't necessarily have anything to do with the brain. It actually makes a lot of sense that a weak heart-popping spell might look like a ruptured aortic aneurysm.

My problem with the theory is it is boring. We already had the story where an earlier event was practice for a larger version of the spell. Why do it again?

Infection should have been obvious by then,

Unless it was a recent infection. When Harry ran away, HWWB found him very quickly. What if Justin learned HWWB was in the area and then found out Elaine had skipped school and was acting strangely? Justin concludes her strange behavior is the result of infection (and he could be right) and conducts an enthrallment ritual to cleanse her. In GS, Harry and Molly have practice mind-wars to train in mental defense magic. It follows that Nemesis infection, which seems very similar to a form of enthrallment, might be countered by actual enthrallment magic.

When Harry gets home, Justin wants to test him too. Again, because Justin recently learned that an Outsider recently arrived in the area. When Harry runs away, that confirms (in Justin's mind) that Harry must have been recently infected. When Harry comes back, Justin tries to cleanse him. When Harry fights off the enthrallment, Justin decides to open a gate to the NN, push Elaine through where he knows someone from Summer will be there to help her, and then either died before he could escape himself or took advantage of Harry's attack to commit non-permanent suicide.

I can think of several reasons why Justin decided to let Harry win after Harry resisted. First, Harry resisting the enthrallment proved he wasn't infected. Thus, Justin knew Harry was an innocent and didn't want to kill him but lacked the energy to incapacitate him again without hurting Harry. Second, with the house burning down and the heavy use of magic, Justin knew he wouldn't be able to subdue Harry, enthrall him to cleanse him and then hide Elaine and Harry without the White Council finding out. Or third, Justin was surprised by the display of power from Harry and was concerned Harry's new power might be from a deal with Outsiders. Thus, Justin couldn't be certain he could defeat Harry and focused his efforts on saving Elaine.

How would enthralling someone test them for Nemesis? In GS, we learn that Harry has been training Molly in mind magic in unsanctioned ways to defend against mental invasion magic. The way Nemfection works seems highly related to enthrallment, so it seems likely that enthrallment magic would be the most effective way to discover or reverse Nemfection.

If the above is true, then why did Justin wait so long? Well, enthrallment magic isn't benign and likely has the potential for permanent damage. Perhaps it is worse on young people so Justin wanted to avoid it as long as possible. Maybe Justin didn't ask Elaine to stay home from school. Maybe she did that on her own. Justin found the behavior suspicious and having also seen evidence there were Outsiders in the area, had reason to believe (perhaps correctly) that Elaine had been recently infected. When Justin tried to explain, Harry ran away instead of listening. When Harry came back,  Justin thought that Harry had also been infected and tried to enthrall/cleanse Harry. When Harry resisted the enthrallment, maybe that was sufficient proof he wasn't infected. Having discovered Harry wasn't infected, Justin didn't want to kill him, but as Harry provided no opportunity to explain, the best Justin could do is push Elaine into the NN where he knew someone from Summer would be waiting to help her and then took advantage of Harry's attack to commit non-permanent suicide.

Harry could be wrong.

Also, Mab can learn. Mab could believed have believed that she could make Harry her monster in GS and then, when Harry defied her, she learned that she was wrong and obtained a better understanding of free will.

I had forgotten.  Thank you.  However it doesn't change anything.  Cozarkian would have me believe that she is ignorant of the nature of her Knight. That's like owning a gun and not understanding the safety.  Rereading the selection where he awakes in the cave reinforces my belief.

First, I was not asking you to believe that Mab doesn't understand her Knight. I was asking you to believe that Mab doesn't understand the full extent of the power of free will. Specifically, she doesn't understand that Harry giving his oath and accepting the Mantle by his own free will doesn't make him hers to mold. She doesn't understand that the Mantle can be conquered even while desiring a Knight that will fight it as long as possible.

On second thought, however, it is indisputable that Mab does not understand her Knight. I don't recall if it is text or WoJ, but we have definitive proof that Harry surprises Mab. She probably has a better understanding of Harry than he does of himself, but there are some things about him she doesn't understand.

I'm not sure the gun analogy is accurate, but if it was, I point you to the Molly short story. As Winter Lady, Molly is absolutely carrying around a full arsenal of weapons without understanding the safety features on most of them. Mab has a lot more experience than Molly and has learned the safety features for most of the Queen's weapons, but it is possible she still doesn't fully understand one or two.

Kemmler may have thrown a Death Curse - believe that there is a theory floating around that his Death Curse was the Tsar Bomba explosion.

The other side of that theory is that the Tsar Bomba explosion may have been one of the attempts to kill Kemmler.

I can see how you got to that thought, my bad. I wasn't trying to imply that Harry killed Justin with mundane methods rather than magical ones. I was trying to make the point that I don't think he would have succeeded at killing Justin with magical means generally, and so something is unusual and doesn't add up about the duel.

Simple. Justin wanted to die. Prior to his death, Justin was in the process of training two potential starborn. One, Elaine, had already been successfully enthralled. The other, Harry, had proved to be too troublesome to be worth the additional effort as Justin only really needed one potential starborn, so Elaine was sufficient. The next phase in Justin's long-term plan required him to fake his death so he could disappear from the public eye. Since Justin knows how to actually come back from the dead, Harry's attack provided a convenient cover-story.

Not necessarily. Here is the definition of "lie" I found:
If the seven words were using the second definition of "lie" then Uriel is in the clear to say them. We have a WoJ that Mab could say that she could change Harry because she believed it to be the case, given her past experience with Winter Knights. Thus, Uriel was just saying that her claim was founded on a mistaken impression, which indeed it was.

The difference between a lie and a mere mistaken impression or falsehood is in the knowledge or intent. In the example you used, the married woman would be "living a lie" if, for example, she was pretending to love her husband when she knew that her feelings weren't real. Or maybe her spouse was a criminal and she was pretending her spouse was an upstanding citizen. Either way, it is about willful blindness. I don't think the Fae can do that - their subconscious would force them to confront the truth by preventing them from lying. Mab would have been physically unable to speak those words if she was merely hoping to live a lie by lying to herself.

Why wouldn't Uriel be able to lie? He's the spook, I think he CAN lie, just not in a way that compromises Free Will.

I think DonBugen handled this question quite well, but even assuming Uriel can bear false witness on some occasions, lying to somebody when you are telling them something it is extremely important for them to believe is not very smart. E.g., 2 + 2 = 3, trust me, Mab can't change who you are.

More importantly, he says lies. He doesn't say 'Mab lies' he says 'Mab's words are lies'. A semantic difference, but if Mab is wrong and doesn't know it, you could argue her words are still lies withou Mab lying.

Mab lied, Mab's words were lies, and Mab told a lie are all synonymous. The fact that you felt the need to specify that "you could argue" is a clear indicator that "semantics" is a poor justification for using the word Lies. Either JB made a poor word choice by using "Lies" over the equally available and more accurate choice of "Wrong," or JB chose the word lies because Uriel and was not the actual speaker and the word choice was tailored to the character speaking. JB isn't perfect, it's possible he just made a writing mistake, but in this case I don't think he did.

We should also not forget, that when Uriel in Ghost Story reveals the seven words whispered to him by the Fallen, that scene is different and that thought does not actually occur in the text during Changes. Even though we learn his memory was altered by Molly, that scene does not actually exist in the text of Changes.

Agreed, but why is that important other than that JB skipped the scene in Changes for story-telling purposes?

And I do agree, just because Uriel called Mab a liar doesn't mean Mab though she was lying. She simply assumed what she said was truth. I don't think the fae have to tell objective truths, only believe that they do. Otherwise the fae would be WAY more powerful than they are. I think the only beings that might fall into that category are beings with Intellectus (funnily enough, like Archangels and the Mothers).

If Mab didn't think she was lying, then Mab wasn't lying, she was simply wrong. Telling a lie requires knowledge of the falsity of the statement.

Mab's lie is a lie of omission.

That just doesn't fit. I don't think Mab was being clever and trying to mislead Harry into believing something that wasn't true, I think Mab believed what she said was true and she was simply wrong, because she doesn't truly understand free will.