(The following conversation is entirely telepathic for reasons that should be obvious.) Fate: "Vita, what did we tell you not to do in this area during the briefing?" Vita: "If I recall, it was something like, 'Do not go into the cavern, or they'll trap us and have us be burned at the stake.'" Nanoha: "You remembered correctly. Now, what did you do a few moments ago?" Vita: "...I went into the cavern..." Nanoha: "Speak up a little louder, please." Vita: "Alright, fine. I went into the cavern. There, you happy now?" Fate: "Not until we can get ourselves out of this alive."
(The following conversation is entirely telepathic for reasons that should be obvious.) Fate: "Vita, what did we tell you not to do in this area during the briefing?" Vita: "If I recall, it was something like, 'Do not go into the cavern, or they'll trap us and have us be burned at the stake.'" Nanoha: "You remembered correctly. Now, what did you do a few moments ago?" Vita: "...I went into the cavern..." Nanoha: "Speak up a little louder, please." Vita: "Alright, fine. I went into the cavern. There, you happy now?" Fate: "Not until we can get ourselves out of this alive."
If the fire is magical fire like Signum's, then they'd have a problem. Otherwise, they'd be fine, because conventional fire can't hurt them while they are in their barrier jackets.
Also can't Nanoha just conjure up some accel shooters and blast their binds??
It... depends on the fish being depicted, I suppose? Where are you seeing these images? Because if it's a Comma Swordtail she's wielding in the images, the joke's pretty easy to figure out.