Sadness thought a lot about some of the video games Riley played. How who wen first was determined by their speed. Pretty smart. But that thought was usually followed up by 'But my speed is zero. And she doesn't even know she's playing. So we'll never finish.' and then she got sad again.

She wouldn't specifically say she had a crush on Joy. I mean sure, she couldn't help but stare whenever she first saw the taller emotion. And she sometimes(always) spied on her when she was on dream duty. And she drew pictures of her ice skating and dancing and SMILING AND GLOWING-
OK fine. Maybe she had a crush.
But it didn't matter. She could never ask Joy out. She'd just screw it up somehow, and then things would be awkward, and they'd slowly drift apart, and then Riley would suffer, and then Joy would be angry.
And Sadness could not take that. Especially not if Joy was angry at her.
She cursed her own inherent pessimism, but she couldn't break herself out of this cycle. So she made herself be OK with just knowing the emotion as a friend. It beats not knowing at all.

"Welp guys, that's us!" Joy exclaimed cheerily as Riley's eyes closed and she lost consciousness.
"I think Joy and Sadness should do dream duty tonight."
It took every iota of Sadness's being to not whip her head around to Disgust. What did she mean by that? Did she know? Was she being that obvious? Oh God if she was that obvious then did Joy know?
"Perfect! I-uh-excellent! I mean excellent. Everyone else off to bed now!" Joy said, literally pushing the other three off and, in Anger's case, throwing them into their rooms. Shutting the last door, she turned around and raced back to the controller, pressing the button for some chairs to pop up on the way.
"Ok! Let's get going!"

"Happy or sad?"
"Her dog died. I'm gonna say sad."
Joy conceded, taking her hands off the controller and Sadness placing hers on. The blue memory rolled out and clinked against the other dreams she had tonight against the rest.
When the next dream appeared, it was just scenery. A beautiful hilltop, butterflies fluttering and a light breeze blowing the flowers.
"Huh." Sadness said. "I guess this one is happy."
"Sadness."
"Ok ok. It IS happy. There's no way this could be sad."
"Sadness."
"What you think it's a mix? I mean I don't really see-"
"SADNESS."
Turning her head, Sadness started a "What?" but it died at "Whhhh" because when she turned, she saw Joy's face was close to hers.
Very close.
Their noses were touching.
Without a word, and seemingly without conscious thought, both of them maneuvered their faces closer until they were actually breathing into each other's mouths.
Nothing moved.
Joy moved her head the extra distance, and now they were kissing.
It was slow and awkward. Just lips and a weird side hug. But neither cared. Because they both knew that is was the beginning of something great.
Sadness smiled as she realized not only was Joy playing the game, but she had won.