The answer for Chen and Ran is obvious. Save each other because they're weak to water and let Yukari save herself.
Urk.Eh?Oh, me?Waaaaah! Ran-shama, Ran-shamaaaa!Ran-shama...The waterrrr!The water...Contagious tearsHopeless, the both of you!Nngh...I am most ashamed...W-...well, my duty is to be your familiar, of course, Yukari-sama...Yukari-sama!If she can't make a decision like this in an instant, then...I'm doing this too?What are you saying?SlummmpBawwwwWhat choice would you make, Yukari-sama...?.... In-... incidentally...All right, Ran.It's cold! My formula's come loose, Ran-shamaaa! Gggnnnngghhh...If that's how things are, no matter how much time passes, you'll never be fit to act in my stead, do you understand?Isn't it obvious?GloooomGo a little easier on her!!!Good grief!F'nyuu...Provide an example.
I believe it is my duty as a familiar to give priority to you, my master, Yukari-sama...