There is indeed one historical Nicodemus outside the bible, apparently (though some scholars suggest they are the same, I think that's reaching... the first was accomplished around the year 30, the second Nicodemus was active around the year 70). And wikipedia mentions it's not sure if the name has Hebrew or Greek origins. So trying to answer which Nicodemus, and why, seems to risk a rabbit hole...

He doesn't have to believe.
He just has to be really, deeply, good... all the way down (and strong enough to bear the burden).

Just like Butters, whose Faith is evidently Jedi not Christian.

I fully expect Dresden and Lara to get married and while their union is not their idea and may only be done begrudgingly, it won't be done involuntarily.  I expect Butcher to make their acquiescence logical and the 'least bad' alternative for them - and that's without considering Mab's wrath if they don't get married.  Butcher is great at maneuvering Dresden into a place where a decision he makes isn't one that he wants to make but feels he must due to necessity from obligation or responsibility.  I'd be surprised by romantic love between them, but certainly a high degree of respect (even though Dresden will likely always think of Lara as a monster; to him, 'she's a monster, but I can respect her, trust her word, and work with her').

The bigger question to me is whether there will be consummation.  I expect so because Mab will demand it.

My theory:  there is no Maggie in the Mirrorverse.
Susan & Harry's story was just very very different.

Gentleman Johnny also very very very much wishes to be his Own Man.
And that is fundamentally impossible for a KotBD hosting one of the Fallen.

But the un-Fallen?  They are all about that Mortal Free Will.

If John ever comes to understand that, he'd flip sides in an instant.  Of course, it'd take... errr... some "other changes," let's say... for him to become eligible to become a KotC!

For that to happen,  Marcone will have to take Sanya's route and give up his coin.  There's already a Jewish Knight and an agnostic Knight, but I don't think Jim would propose for anyone to hold a coin and a sword at the same time, even temporarily.

Harry will pull a move from Skin Game.  There he hired Goodman Grey before Nichodemas could when they went to plunder Hades vault.  When he goes back in time in some upcoming book (breaking one of the laws) he somehow runs into Goodman and hires him before the other version of him. (When hehires him to watch Justine in Peace Talks -or- Battle ground).  Goodman then doubles Murphy like he did with the Accountant in Skin Game and it's really him who was shot in the neck and he has her hidden until he returns from the past to not cause a paradox....etc   Since he's a Negloshi (sp?), the shot to the neck won't kill him..

Something ghost related. After Ghost story I think it was maybe Odin or someone says how he "has crossed the boundary of life and death, opening himself up to options/things that will take notice of him..."     Or something similar to that.   So maybe in 12 months while in his new castle he has learned things related to that which allows him to talk to her.  He did make the comment in Battle Ground about maybe it was time for him to start learning some new things after River Shoulders (Bigfoot) offers to teach him..