just going by what's in the species lore for druids, they're very in tune with nature, so my thought was that when he's around her garden (if she has one) flourishes and he may have a sacred grove of trees nearby where he does his rituals, maybe a stone structure, things that kind of pop out of nowhere but at the same time still feel like they've always been there.
i love that idea, that they see each other in human form often. she could potentially think he's a neighbor. i think he probably seeks her out when the weather is bad and he needs shelter, because truth be told i feel like he's mostly a vagrant. he doesn't have his own place and just curls up wherever. he survives off of his ability to make produce grow quickly for his meals like some raw food vegan shit. and most likely he's a rabid environmentalist. but i don't have too many details yet!