Spoilers!!!! Carlos's apology from the lot of you, SC IS THAT DUMP

[Mira]

It's the Dresden multiverse.  In one verse Carlos Ramirez is Harry's secret ally.  In another Carlos Ramirez no longer trusts Harry. 

If the emoji doesn't tell you, I absolutely hate this idea.  Please consider the above to be a bad joke.  If it turned out to be the correct explanation I would be greatly disappointed.  It would allow Jim to do almost anything with his characters, with little rhyme or reason for changes in their behavior from one novel to another.  Worse, the remaining novels in the series should be setting up the finale.  If major supporting character's behavior becomes erratic, it could, probably would make this setting up phase less coherent and the reading far less enjoyable.

Exactly, why the change in attitude when Carlos first shows up at the castle?  Nothing in-between, if they met by chance, or if Carlos took Harry aside or it that last meeting in Battle Ground hadn't been so absolute!  Why is Harry so trusting of Carlos all of a sudden after Carlos really stabbed him in the back and kicked him when he was down at the end of Battle Ground?

It seems the most obvious reasoning. Harry sends Toot out to alert people. Harry isn't at all surprised that Carlos shows up.

But Toot doesn't know that Carlos is team Harry now does he?  Odd don't you think that Carlos is there minus his cloak and says he isn't there.  That smacks of pre-planning.

[Bad Alias]

But Toot doesn't know that Carlos is team Harry now does he? 

Doesn't matter because Harry told him who to alert.

I dropped to a knee in front of him. “I need messengers sent out. Tell these people I need them here by sundown, and to come prepared for a fight. Got it?” I fired off a rapid list of names.

Odd don't you think that Carlos is there minus his cloak and says he isn't there.

Yes. One thing is that it seems Harry isn't supposed to have any contact with the members of the White Council. It's not stated explicitly, but it appears to be a condition of warlock protocol.

[Ilyana] turned to me. “Have you had any contact with any member of the White Council?”

[g33k]

...  Was he hanging out with Butters and Father Forthill watching the boxing match, and heard about it at the same time? ...

I suspect he may have been, actually.
Because it seemed an awful lot like Forthill and Aaronson arrived in coordination with Ramirez -- they knew he was veiled, part of their approach was to help his stealth.

I think Carlos was raised Catholic -- he still curses with Dios! and other religious curse-words, not Harry's supernatural "Stars & Stones!" -- and maybe he has a connection with Forthill by way of a similar priest back in LA, likely another member of the Ordo Malleus (this might give Carlos some "cover" with the White Council, interfacing with an ally is a legit non-Dresden reason to be in Chicago).

[Dina]

Yes, I agree.

[Mira]

  I say, "God" or "Dios" a lot, I am not Catholic.  So just because Carlos says "Dios" a lot, doesn't make him Catholic, he is also of Latino heritage.  You could be right, or Carlos saying, "Dios," shouldn't lead to the assumption that Carlos is Catholic.