The Wheel of Fortune is a 4x4 sized tile. The Count's city is 4x3.
How exactly does the Dragon interact with these tiles when it's moving? Same question for The Plague's fleas. I can guess it's one of these 3 options:
A) The Dragon and Fleas can't occupy these tiles and have to go around. The Meeples on the wheel are safe.
B) The Dragon and the Fleas can occupy these tiles and everything inside dies. Then they can move to any adjacent tile.
C) The Dragon and the Fleas can't occupy these tiles but they can "jump" to the other side.
So what is it?
The dragon and the fleas can occupy the outer areas (you can see the lines serving as tile separations) of the city of City of Carcassonne and the Wheel of Fortune but the dragon cannot get into their interior area, so any figures inside is safe.
There are official clarifications about this for the dragon, and it was made extensive for the Plague, due to the similarities between these special features.
>> The dragon and the City of Carcassonne:* Note that the dragon can still move onto tiles that include the City of Carcassonne, treating the landscape areas as normal tiles, but it must stay outside the City itself. Thus only figures outside the City are eaten, and those inside (including the Count) are safe. (12/2013)
You can find this clarification here:
http://wikicarpedia.com/index.php/The_Princess_and_The_Dragon#Dragon* The dragon can fly around the outside the city of Carcassonne, treating the landscape areas as normal tiles and eating any figures on those tiles. Meeples and the Count inside the city of Carcassonne are unaffected. (10/2012)
You can find this clarification here:
http://wikicarpedia.com/index.php/Count,_King_and_Robber#The_city_of_Carcassonne_and_the_count_of_Carcassonne_2>> The dragon and the Wheel of Fortune:* The dragon can fly around the outside of the Wheel of Fortune, treating the landscape areas as normal tiles and eating any meeples on those tiles. Meeples on the Wheel of Fortune itself are unaffected. This represents a notable change from previous FAQs. (10/2012)
You can find this clarification here:
http://wikicarpedia.com/index.php/The_Princess_and_The_Dragon#Dragon>> The Plague, the city of Carcassonne and the Wheel of Fortune:* Given current interpretations regarding placement of the dragon and followers on features outside the City of Carcassonne and the Wheel of Fortune, it seems that the plague should also be allowed on the outside portion of these tiles. However, this is unofficial. (1/2013)
You can find this clarification here:
http://wikicarpedia.com/index.php/The_Plague_(1st_edition)#cite_note-4>> The dragon, the Plague and the city of LeipzigAs a bonus, I will include a note on the city of Leipzig. Due to its similarities to the city of Carcassonne, we should apply the same rules: the dragon and the Plague are allowed outside of the city of Leipzig, but the interior is protected from them. This is unofficial, since HiG is not providing clarifications about the interactions with minor expansions since 2016.
Additional question: what about German Castles and Markets of Leipziig tiles? Do they count as 2 normal tiles, with the Dragon and Fleas affecting only half of it? If a Meeple is occupying the Castle, must it be placed on one of the two halves to make it clear if it's affected or not?
The double-sized tiles featuring German castles and the Markets of Leipzig count as one tiles for the dragon and he plague. There are official clarifications for the dragon and the Plague from 10/2015. So there is no need for the meeple to be positioned on any half of a double-sized tile. They are just one tile.
You can find these clarifications here:
http://wikicarpedia.com/index.php/Castles_in_Germany_(1st_edition)#Other_expansionsThe original CarcC dicussion about these clarifications is next. Check questions #5 (the dragon) and #8 (the Plague):
http://www.carcassonnecentral.com/community/index.php?topic=2125.msg29585#msg29585