Ionine.

I was delighted to read this article about violets, because I think it speaks to the essence of my own Violet very well:

There are plenty of scents that we become accustomed to over time. We smell a perfume that gets spritzed on us intensely for the first five minutes or so, less so over the next hour, and finally we tune it out like we would any constant stimulus — the feel of our clothes against our bodies, the exact shade of artificial lighting at work. Violets are something else. They can't be entirely tuned out.

It goes on to explain how violets get their scent from ionine, which stimulates, then binds to our scent receptors and temporarily shuts them off completely. After a few breaths, you'll be able to catch the scent again, rather than becoming immune to it, as it is.

That's Violet, she of such sweetness that lingers. She goes quiet, retreats into herself for a time, but before long you'll hear her flitting through the house, or see that smile that lights her eyes, or catch the light bouncing from one of her many bracelets. And there she is again, all sweetness, tugging at your sleeve, crinkling her eyes, announcing, "I wuvs you, Mama," before pattering off again.