Again I would like to thank 04Lonewolf for their point which was

"If Marinette originally got the Cat Miraculous instead of Adrien (And Adrien got the Ladybug) Do you reckon that would mean Adrien would fall in love with Marinette and vise versa (so Ladynoir would have fallen in love with Mister bug.)"

I'm not entirely so on this one because there are so many factors  that could change this, but this is just based on my opinion so um. Here goes.

I lay ramble a bit since I'm not just going to be talking about the relationship between Adrien and Marinette.

Before this continues though I will say that I'm exculding complete roleswap where Adrien lives at a bakery and Marinette lives in a mansion because that would pretty much be an opposite parallel of the show if that makes sense.

Anyway. This would change quite a few things

(First I'm going to talk about how I see their personality as.)

For instance Master Fu probably would of met Adrien first and he would end up being the guardian however his actions as Mister bug would be quite different from Marinette's actions as Ladybug.

And so would vise versa.

I know that in Refelkadoll (sorry if I spelled that wrong) we got to see a bit of this switch, but to be honest I found that episode pretty disappointing.

In that episode it makes Adrien seems like an idiot who cannot come up with plans by himself.

Especially since the lucky charm he got became obvious after they saw that slim hole however Ladynoir actually had to say the word coin for him to figure it out.

And that's why I cringe a bit at the episode since they downplayed Adrien a lot in it saying his job wasn't that important and was very easy and that he was basically just a sidekick.

That's just how I saw it as, but that's all the resource I have to see how their characters would act if they did have opposite roles.

In the episode Adrien as Mister bug acts a bit like Marinette when she is Ladybug. (He didn't like it when she called him Bugaboy and he wasn't making many jokes.)

Marinette as Ladynoir acted a bit like Adrien when he is Chat Noir (She made more jokes than usual.)

However this is not the kwaimi's doing from what I've heard.  The kwaimi's don't change the personality of their chosen when they transform, so when they transformed into.

This episode is saying that whoever has the Ladybug Miraculous has more weight on their shoulders. (Sadly, the person who wears the cat miraculous is a bit in the shadows, but the new York special made me happy.)

But back to the point I think that

In this au I believe that Adrien wouldn't be as happy.

When he was Mister bug, he got annoyed at Lady Noir a few times..just as Marinette would get annoyed at Chat Noir.

Because of this I do believe that Adrien would most likely fall in love with Marinette rather than Lady Noir because she would be one of his first friends that he could rely on. (Not actually his first though since he has Nino and he counts Chole as a friend)

That could be wrong though because I'm actually not sure if Marinette would love Adrien when he is Adrien or as Mister bug.

Since when they first met Chat Noir had to comfort Ladybug and I believe that would still happen, but if that was the case then so would the umbrella scene.

Mister bug makes less jokes then Chat Noir, so Marinette would probably find him less annoying. (I personally don't think he is annoying, but that's my opinion. )

So..I'm not exactly sure if Marinette would fall in love with Mister bug or Adrien.

If she fell in love with Adrien then he may not fall for her at all since she would always be stuttering..and he may have a hard time expressing his  problems with her..

I highly  believe that Adrien would fall in love with Marinette in this Au and that Marinette  (Not entirely sure why.)

However honestly I'm not completely sure..

Again this is all just my opinion though.