You are all in for an absolute treat of a read: Janus Rose, a Severus/Pomona story written for the severus_shorts comm (which features stories looking at Severus Snape through his lifetime of birthdays).
This beautifully-written fic creates moving, believable pictures of Snape and Sprout, and it does so in ways that I love -- by making magic and vocation integral to the narrative and to our understanding of the characters. Magic and herbology and potions are not external parts of the setting, or background details put in just to make clear that we're in the HP world; they are the essence of the tale and the people in it. (I admit, though, that had I written this story, I would not have ended it this way. I'll be interested to hear what you all think. This story is so strong that it will stand up to some good literary argument.)
"The Janus Rose" is the first and only Severus/Pomona I've ever seen, but damn, I hope it is not the last. You know how militant I am regarding the need for believable romance and relationships for the older-women characters of HP -- and here's a fic that shows exactly the pleasures and possibilities that I'm talking about!
And it also does a fine job with Sprout, a character sadly underused both by JKR and by fanficcers. I love Pomona and often work her into my stories, but so far, I've always featured her as a side-kick only. I need to remedy this situation: "The Janus Rose" makes clear that we need more fic with Pomona in a starring role. I need to get busy on that Minerva/Pomona I've long been considering...