He takes her to see the cherry blossoms. When she is sad. When she is angry. After days when not everybody lives.
It begins when she watches Memoirs of a Geisha on the TARDIS the night after Adam nearly gets them killed. The next morning, the Doctor brings her to a lavish hanami festival in the height of the Heian period.
Rose adores the subtle beauty of the delicate blossoms and their sweet perfume. She delights when the wind blows, laughs and says it's snowing petals. He tells her about the planet Meil-yume, with trees so high it really does rain flowers.
She doesn't find what she's looking for in 1987. Rose witnesses the perils of paradox and his hearts break to see her hope and despair and grieve. She stays in her room for a while and they don't go anywhere. When they finally do, it's straight to Meil-yume, the planet of the raining flower petals.
It's the Cherry Blossom Festival in Washington D.C. after regeneration. A bit of continuity. The same beautiful flowers alive against cold stone monuments to dead men. So many people, noise and language and conversation, all drowned out by Rose's brilliant smile.
Mickey stays behind in Pete's World. Rose meets her father and loses him again. Watches her mother die only to find her alive at home again. The Doctor wafts around the console, a petal floating on the breeze. The coordinates set for Japan.
Rose is captivated by yozakura. Paper lanterns hang in Ueno Park, their gentle glow illuminating the sakura trees to the night. They could be stars or suns or just a distant fire. In each glimmer, the Doctor sees her. Burning brightly with the borrowed power of time and destiny, life and death.
Now, he's hoping to drown out the foreboding voice of an ancient beast even he can't comprehend. It scares him. And if it scares him it must terrify Rose. They're in modern Japan today, walking along the Kamo River in Kyoto snacking on street food. The multitude of pink blossoms on the horizon rival the mountains. There's a lazy wind carrying the dulcet fragrance all around them.
"They're beautiful today," the Doctor remarks thoughtfully. "Right at their peak."
Rose nods, but she's distracted. "They're always the same, though. Next time, could we go see them in another season?"
"Why?" he bites back harshly. "I have the TARDIS, Rose. We can go to any time, any place, and see the blossoms just like this. Perfect. Why would you want to see a dead tree?"
He really has no reason to be angry. It's an innocent question. But she's zeroed in on the reality of these fragile flowers with one sentence. Beauty lauded by poets and emperors. Blooming every spring only to fade as quickly as a strong wind.
In his mind's eye, he sees Sarah Jane Smith. Sees Rose in ten years, in twenty. Why can't they just enjoy the spring at the height of its magnificence, over and over again?
"Okay," she cedes peevishly. "Forget I asked."
But he can't forget. He tries. Likens Rose to the most celebrated of flowers at their pinnacle. Ignores the laws of time and ruin. Believes he can preserve her the same way he keeps these perfect flowers, ready and waiting to visit at her whim.
"No, you're right," he says by way of apology. "Let's see them in the winter. A different kind of snow."
She smiles that same luminous smile she gave him the first time she saw a sakura flower. Two springs come and gone, new eyes, a hundred planets and people and adventures - that smile hasn't changed.
All things are impermanent.
Cherry blossoms flourish, then die, then flourish again.
The Doctor dares to hope.