The short version of the question is: can you stun a character while it is in the chain zone?

Relatedly: do you control a character that you have placed on the zone?

Finally, can you stun a character while it is in the chain zone?

To expand. When you start a recruit effect the character to be recruited goes on the chain and is, therefore, in the chain zone.

I have Dr. Doom in Play and no other characters. Not teamed-up with anyone. I put Floronic Man on the chain. My opponent plays Betrayal while FM is on the chain. What happens next?

a) I have to stun a character but can only choose Dr. doom.
b) I have to stun a character and can choose which one to stun.

Finally, could I use Mikado and Mosha to stun a 1 cost character while it is on the chain (e.g. Boris)?

only characters can get stunned

characters are character cards that are in play.

....what's on the chain (representing the recruitment) are character cards

i know.... it sounds like nitpicking.... but that's how it is.

also... you can only "control" something if it's in play.

so, to answer your questions:
1 - you don't have to stun anyone... you don't control any characters that don't share a team affiliation with Dr Doom because you only control Dr Doom.
2 - nope.... you have to target character and Boris (on the chain) is just a character card

There are a number of subtle distinctions involved here. You control your effects on the chain, so you control Floronic Man's recruit effect. However, the rules also say that you can only control cards in the in-play zone; you control the recruit effect, but not the card which represents it while it's on the chain. Luckily, this somewhat nebulous distinction isn't likely to matter often.

The more important distinction for your question is that between character cards, on the one hand, and characters, on the other. Character cards are only characters when they are in your front and support rows, so a character card on the chain is not a character. It doesn't get factored into Betrayal, it isn't a legal target for Mikado and Mosha, etc.

Ok. Thanks for that. The answers confirm what I had thought to be right but did not have an explanation for.

I'm impressed with the rules answering forum, by the way. Tends to be very fast and seems to be very accurate. Kudos to all involved.

Let me just check if I have this correct.

Once your character card goes in the chain (i.e. all choices are made and all costs paid) it has been recruited. You control the character card however, until the recruit effect resolves you don't control the character. Correct?

So in effect, once Dr. Doom is on the chain I can Reign of Terror before he resolves however, assuming I control a Fantastic Four character, I can't play Common Enemy until Doom's recruit resolves since I don't control a Doom character yet (assuming I have no other Doom characters in play of course :P).

Correct

Correct

wait..... what?

you're considered to have recruited a character before the recruitment resolves?
i'm gunna take a spin through the CRB for this one.... it just seems very counter-intuitive (which, ironically, makes it somehow MORE credible)...

..
.
.

.....so, it would be too late for someone to ready their Slaughter Swamp when the character comes into play?

(this is really blowing my mind....)

EDIT:
ok... here it is:
....huh........
you learn something new every day.