I don't think reading Dresden Files is really needed as only a small part of it was shown. If you know them, it would only leave you disappointed by Nicodemus.

 

While not at the level of some of the stories mentioned so far, I think the following are at least decent - how well they remain in-character is more of an iffy subject, but they seem to meet the other requirements in my humble opinion.

Sirius Interruptions
Sirius Black did not die the night he fell through the veil within the Department of Mysteries; he was cast through the dimensions into another world. Now he must adapt to wandless magic, the dangers of evocation, and learn to deal with the Warden assigned to watch over him, Harry Dresden.

The last Dragonrider
Crash-landing into the next dimension of his trip, Harry finds himself in the middle of Alagaesia and a struggle much like several others before. This time around, he has the joy of raising a rowdy Dragon while trying to figure out whose side of the stirring war he should pair up with, if either. And of course, puzzling the ins and outs of the local magic system superseding his own.

 

Would that be Deathly Hallowed by Shujin1?

 

Yeah thats the one. Good stuff.

 

It seems that nobody mentioned search by tag - see https://forums.darklordpotter.net/tags.php?tag=crossover

 

Here are some awesome ones if anyone got lost searching by tag.

The Master of Death by Ryuugi Shi
In one world, an old man's life ends. In another, a foolish wizard performs a ritual and calls upon the Master of Death. And in both, there is a sound-a sound like an oncoming train. To the well-organized mind, death is but the next great adventure

Fictional by Dark Syaoran
The dictionary defined fiction as thus: something feigned, invented, or imagined; a made-up story. The act of feigning, inventing, or imagining. Yes, Harry thought, this defined him nicely. Harry Potter & Fate/Stay Night Crossover.

Death's Knight by Heather Sinclair
AU Death of the Endless offered Harry a way to save his friends and a few billion other people while he was at it. There's a catch. He has to use that Master of Death title that's hanging over his head and give up almost everything he's ever known. But there are perks. Oh yes, dating a Kryptonian can be challenging. Harry/Power Girl.

 

That story got me into the Dresden stories. At first I was just interested in Harry being a badass half-demon with a sword.

 

Yeah, haven't heard a thing about the first in forever. But last Dragonrider did update a couple of months back surprisingly enough, so maybe's there is still hope for the first.

 

As scaring as most Supernatural fanfics are, I think this bucks the trend.

Illusions of Grandeur by Kanathia Angels, demons, and Winchesters have made it to the top of Harry's black list, but first impressions are rarely right, and a glass of scotch can soothe anyone's temper. Starts mid season 3 and spans several seasons.

A new twist on the Harry in another universe. Very well written and the dialogue is great, characterization is spot on for the Supernatural characters but Harry is intentionally OOC, with good reason as is explained throughout the fic.

Unfortunately, the author has taken a break due to surgery and likely won't be posting for a while. Still well worth a read.

 

What I didn't like about that fic was that the author tried so hard to follow the original story that Harry wasn't consistent at all. But hey at least it wasn't slash.

I think this story was put up for review, or was it Barely Recommendable?

 

I put it up in almost recommendable. No idea if someone put it up in the Review Board.

 

HP/X-Men by dellacour:
HP and the World that Waits

HP/Avengers by Sythe:
Mirror, Mirror

Both are WIPs, with slow updates. Does anyone know if the first one is abandoned?

 

2 years without so much as a peep from the author? I feel safe saying that this one is abandoned.