OK. Let’s see if I have this right. It’s a lingering scent, “leftover” from the past right?
You want “mystery and loss” Old-fashioned rose might do the trick. Rose can smell both nostalgic (loss) and spicy (mysterious). The flower itself implies secrecy, romance (red), and wealth (yellow), even remorse (white). The nice thing about using rose-scented incense is that you can legitimately make the scent indicative of almost any emotion you want it to be. Since rose is a very common scent to use for incense, it makes the idea that someone would be using it very probable and believable.
The rest of this post is just my own ramblings:
Descriptions of incense can be a little “fluid.” Incense will smell differently to different people, and also can change depending on the environment. Let’s say we’re burning pure frankincense. If the smoke is heavy, it might have a lemon-citrus scent. If it’s light smoke, it might be more like burning applewood–smoky, but with faint undertones of something sweet. Rose scented might come across as spicy when it’s light but if it’s heavy, the old rose scent is unmistakeable. Myrrh can smell both bitter and sweet at the same time. Not bittersweet, but more of two at the same time rather than two blended into one.
Here’s some symbolism that might be associated with certain emotions:
Myrrh: funereal “myrrh is mine, this bitter perfume, breathes the life of gathering gloom, sorrowing sighing bleeding dying, sealed in a stone cold tomb” that one’s pretty obvious. It can also have an “oily” smell. It was used primarily to anoint bodies for burial. I think it often has a slightly lemon-spice-oil scent to it. Myrrh might smell oily in the sense of a fine, freshly oiled quality leather, or it might be oily in the sense of a fry pan left on the stove too long that begins to burn.
Pure frankincense can also have all of those scent characteristics, but without the connotations of the word “myrrh” which unmistakably symbolizes death.
Rose: invokes a sense of secrecy or mystery. “Sub rosa” means “in secret” because the ancient Romans when they gathered for a secret meeting used to hang a rose over their heads as a symbol for secrecy. Break the secrecy, and you’ll find yoursel at the bottom of the Tiber in a pair of cement sandals. It could also mean luxury, or even remorse.
Lilly: another scent associated with funerals and death
Lemon or other citrus: might invoke images of childhood innocense or a pleasant, carefree existance. I’m thinking lemonade here. This is just my own thoughts.
Lavendar: this is often considered an “old fashioned” scent. It could evoke images of a time gone by, an old-fashioned garden. Smell lavendar and you’re back in the old days sitting on grandma’s porch.
Spicy, like ginger or cinnamon: intrigue, excitement, adventure, exotic
Cedar: long-lasting, preserving, could evoke thoughts of Solomons temple or a rich Jerusalem merchant.
Jasmine: makes one think of the “old south” and that could have either a very positive or very negative meaning (and might fit with your story line). It could either mean “Gone with the Wind” or “Birth of a Nation”
Musty: I’d recommend staying away from this adjective because incense is dry, and your readers might have a hard time associating a burning object with a wet smell. People who know incense can recognize it, but most readers would probably find it a little “disconnected”
Something I’m getting at here is that you could have the scent “change” depending on the situation. Now, here, I’m imagining that your characters will be smelling the lingering incense over a long period of time, like decades???
Without over-doing it, you might have your characters recognizing the lemon-spice-oil scent when they first smell it as myrrh, then have the lemon be the predominant tone when the children are in the house, but later, the unpleasant burnt-oil when the situation is gloomy. I’m only suggesting this because it seems like the theme of “change” is central to your story-line. If that sort of thing works, pure frankincense would be a good choice because it can have so many different scents, all competing with each other, and the many scents predominating at different times. It could smell like lavendar when the whites are there, jasmine when the blacks are there, and spicy when the hispanics are there (yes, I know those are cliches, so please don’t read too much into that). The frankincense might have that rich leather smell when the woman is being faithful, but then have the burning frypan smell when she makes her deal with the devil.
Ok. Pardon me, but I’m just having a little fun here and hope you don’t mind my ramblings.
Of course, I’m merely speculating on what you might be doing here with your story. My thoughts might be completely off-base if you want to have a scent that never changes but is consistent throughout the whole of the story.