Bramble had a coughing/sneezing fit a few minutes ago. It starts out sounding like she's coughing up a furball, though nothing's ever come up. When it first happened I rushed towards her, intending to get her off the carpet, which cats always choose to throw up on, but I stopped doing that, partly because there was no furball or sick, and partly because she ran away from me, though never away from carpet!
This time, Lily rushed to her, and I expected her to take advantage of Bramble's distress and pounce on her, but (and I know this sounds anthropomorphic) she seemed concerned for Bramble's welfare. Not only that, but Bramble didn't feel threatened and stayed where she was. I think they've turned a corner in their relationship. There's still the occasional spat when Bramble gets tired of Lily's youthful exuberance, but they're spending much more time close together in peaceful coexistence.
I managed to get a photo, but it was on my phone, in poor light, so it's a bit rubbish.