Re: OCC Jaina will go straight for one because they look a lot like the things she's been fighting back in her world. It will take her a minute to realize that they're not what she thinks they are. It will probably take her seeing one breathe fire (if they do?) or get smacked by a wing to realize it though. If she sees anyone get attcked, she will not hesitate to take it out. No, she doesn't have PTSD from the Yuuzhan Vong, why do you ask?
Yelena will be fascinated because how often do you see a dragon? I'm sure she'll think it would be a cool way to die. She will help in whatever way she can though, getting people out of the way and what not. She wouldn't actually try to go after one but she might think about it.