Ok but imagine Sulu getting injured during a mission and having to recover in sickbay. And he’s all bed-ridden and miserable. Chekov, Jim, Uhura and Scotty all come to visit him - which helps lift his spirits for a while, but after they leave he’s back to feeling anxious and upset. He’s worried about his plants but he doesn't ask anyone to water them while he’s sick. Doesn't want to bother anyone. Feels bad enough at not being able to preform his duty, never mind asking someone to waste their time on his silly hobbies.
So when Spock walks in hours later Sulu is shocked. Mortified that his superior officer (and the subject of his pining school-boy crush) has to see him this way.
“M-Mr. Spock!” he stammers, fumbling with the bedsheets and bolting upright, choking back a hiss of pain as the bruises littering his body protest. Spock’s eyebrows furrow in concern but Sulu reads it as disgust and feels a hot wash of shame rush through his body. “I’m terribly sorry, sir. So sorry. I can’t believe I managed to get hurt so bad on a simple mission. It’s incredibly unprofessional and as a member of Starfleet-”
“Hikaru.” Spock interrupts gently. Sulu cringes at his own outburst before he realises Spock called him by his first name. Adrenaline rushes through is body and he can do little more than open and close his mouth uselessly before Spock continues.
“Do not fret. I merely came by to see how you were fairing. I apologise for the delay of my visit, but I was busy with these,” Spock then places a vase of rich coral and white peonies on his bedside table. Sulu can only stare in complete disbelief.
“I used a replicator for the seeds, and artificially enhanced their speed of growth.” Spock then averts his eyes for a moment in a rare display of nervousness. “I recall you saying to Mr.Chekov that you prefer your flowers to grow naturally, but there was little I could do in such short notice.”
“Mr, Spock, sir.” Sulu babbles after a long moment of silence. He reaches out a shaking hand to gently touch the petals of a why peony. His heart beats violently in his chest. “I don’t know what to say. I - no one has ever...” he swallows thickly. “Peonies...they symbolise healing and recovery. Did you...?”
“Yes, Hikaru.” Spock says quietly, shyly. Sulu’s cheeks begin to flood with colour as the situation catches up with him. “I was aware of their meaning. Might I also add that I took the liberty of caring for your garden while you have been indisposed. There is no need to worry.”
It is at that very moment where Sulu realises he’s never been so helplessly, painfully in love.