The question posed on the fabulous Elsa Elsa board was: Your first clue you are talking to a Pisces?
Ivana so true about Pisces speaking to themselves and to plants, vegetables, etc. when no one is around or when people are around but no one is talking to them. :-)
I also agree with those who said a gentle, soft, watery, ethereal, not-there *quiet* look. But some Pisces, especially female Pisces, can come across very strong and direct (perhaps they have Aries in Mercury or Venus or something like that).
I also agree that ALL the mutable signs have something to do with communicating and sharing knowledge: Gemini, Sag, Virgo, Pisces…