Fire

They say to watch out for fire. Fire burns, it rages wildly, it has a life of its own. Embers smolder, they breath on oxygen, they burn hotter than the flame.

"Love is friendship on fire,"~someone once said.

I would say that perhaps true love is friendship in the heat of the embers, whereas being "in love" is friendship in the heat of the flame. Embers sound better than the flames.