So you would need to make an overlay of your background and have it like this:
INT. BACKGROUND NAME with BACKGROUND OVERLAY at layer 2
&overlay BACKGROUND OVERLAY opacity 0
&MAIN CHARACTER spot directing here
&MAIN CHARACTER moves to layer 3
&FADING CHARACTER spot directing here
@FADING CHARACTER moves to layer 1
(Here, you just need to make sure the overlay background is underneath your main character, but in front of the character you want to fade out because otherwise it will also fade out your MC. This only works if your fading character isn’t standing directly on top of your MC otherwise the Fading Character will appear underneath her, but if that character is standing in a position where it doesn’t cover the MC, it can work.
So, then maybe you have some dialogue. Then when you zoom you want to fade out the character so for example you would then go…
&zoom code here in 4 (or however many seconds)
@overlay BACKGROUND OVERLAY opacity 1 in 4 (make sure the seconds match above to be smoother)
This then makes sure the background will then fade over the character to give a fading effect whilst zooming whilst also making sure it doesn’t fade over the MC.
However, if you character is directly over the MC, I would suggest rather than using fading, to get the character to simply walk out of the screen because otherwise it could get clunky trying to mess with overlay layers.
Obviously if you have more layering you would have to tweak it, you would just need to make sure your MC and anything or anyone else you want on screen is infront of the overlay, and the character you want to fade out is behind it.