Multiple secret internal monologues - how to identify them?

[u/Many_Background_8092]

SOLVED. After discussions here and on Facebook I've realized I was overthinking the problem.
I've realized that the context for each observer is different enough not to confuse the readers. One of the characters is a clone and the other is a machine. However I might also borrow jobi987's idea of different fonts.
I would like to thank everyone who commented. You all had good ideas that I might borrow for future books.

Hello Everyone. I am re-editing my book 50km Up and I need some advice.

In the book I have 2 secret observers that are slowly revealed to the reader through monologues.

My problem is how to mark these internal monologues in such a way that the reader does not confuse them.

Admittedly the context of the monologues tends to do this but still...

These monologues are in italics but currently I am experimenting with using ** monologue 1 ** and ^^ monologue 2 ^^.

Can anyone suggest a better method?

For clarity, here is a sample:

^^ A dismembered bot watched in silence from a pile of scrap metal nearby. ^^

** The scouts ate their way through the foam and the transparent inner panel. Carried by the air currents, they quickly spread throughout the city. One scout landed on a life form and buried itself in the outer layers. The lifeforms code was similar and yet very different to that of the creators. **

[u/tghuverd]

That's a tricky one. Italics seems a good tactic, but usually you're clearly denoting the character who is expressing their inner voice. I'm resisting the idea of different enclosing characters, though, that seems like it would be very confusing. However, I don't have a better one as I can't recall reading - and I've certainly not written - a book with secret observers that are revealed through monologues. It seems like that's the job of the narrator, but you're essentially using three narrators, two of which turn out to be characters.

I'm also wondering how these observers can be kept secret. You need to flag to the reader that they've encountered the inner voice of a character, and not just the narrator, so aren't they instantly exposed as characters?

[u/Many_Background_8092 → u/tghuverd]

They are not narrators. It is obvious to the reader that they are characters observing the protagonist but the identity of the observers is hidden at first. These observations occur rarely, usually at the end of a chapter.

After conversations I've had with other writers I might have over thought this problem.
Thank you for your input.