Sparks

"Sparks are mutual. You will know it when you feel it. I've only felt sparks twice in my life, ever. One I married, the other I avoid." - Whitey from the Lab.

Sparks, huh?

spark1 ( P )

An incandescent particle, especially:
One thrown off from a burning substance.
One resulting from friction.
One remaining in an otherwise extinguished fire; an ember.
A glistening particle, as of metal.
A flash of light, especially a flash produced by electric discharge.
A short pulse or flow of electric current.
A trace or suggestion, as:
A quality or feeling with latent potential; a seed or germ: the spark of genius.
A vital, animating, or activating factor: the spark of revolution.

may sometimes be confused with butterflies. :)