Rain can pretty easily guess from the names which of Bright's two Nature attributes, Insulated and Toxic Heart, is her Quirk. So, he first inspects Insulated.
Insulated
You are naturally resistant to changes in temperature, including attacks that rely on intense heat or cold.
That one makes sense given her powers...she'd give herself hypothermia or severe burns pretty regularly otherwise, even with her durable Demigod body. Feeling like there's nothing else left to do or contemplate, Rain turns his attention to her final Nature attribute, activating its description.
Toxic Heart
Your heart is the poison of your goals. The more emotion you feel, the less control you have over your Talents.
From the moment Rain reads and comprehends the Quirk, Bright's interactions with him make significantly more sense. Whenever he feels the room go cold when teasing her, that must be the effect of this Quirk. That also explains why she always seemed so cold and emotionless to him early on...she's probably spent years suppressing how she feels out of fear that it will cause issues.
He turns to her with a sympathetic expression...in a way, he can empathize. Though it hasn't been truly catastrophic yet, Unhinged works on a similar principle. If he feels too strongly about something, he loses some control over his actions. His voice comes out, apologetic.
"I'm sorry, Bright...if I'd known...I wouldn't have teased you so much. Having your control stripped from you is a bit of a sore spot for me."
As he stares at her, she directs a grim expression back at him, her mood obviously somber.
"The worst your teasing has ever done is chill the room a bit, Rain...that's nothing to me. When I was still a Paragon, I accidentally electrocuted a guy I was dating while we...well...I'm sure you can guess what triggered me. Mortifying as that was, though, I could still get over it. He may have dumped me, but at least he lived. The times that Quirk has made me truly hate myself...it's when it doesn't trigger my abilities.
"Early on, before I learned how to better suppress what I feel, it was easy for me to become unreliable in a fight, losing access to my Talents. If I was up against Fel at a fresh Rift, and things started to look dire enough to scare me...well, let's just say that there is more than one person that might still be alive if I'd been a bit braver. Those people...their faces...that's a lot harder for me to get over."
Rain feels the weight of her words so heavily that he's not even tempted to make a joke about her sex life. Part of that severity comes from the unexpected insight into what could be in store for him. What if he feels the urge to run from a battle to save himself, and an ally dies because Unhinged makes him act on that fear?
He's been alone and isolated so much of his life that the thought of something like that never occurred to him before today. But now...though it's new to him, he has people that he cares about. His dark desire to see Ronin overcome her situation isn't without some level of emotional investment in her well-being, amplified by the time they've spent together getting acquainted.
Nik is someone that Rain isn't personally close with, per se, but he likes him. Respects him, even. More than anything, he's come to quite appreciate the Legacy's company...he considers him a friend, though he doesn't have much prior experience with those to know if their relationship counts. Still, it'd pain him to see Nik suffer over his decisions.
Then...there's Tessa. Out of all three of them, she's the one he's closest to, and who he spends the most time with. On a personal level, they're the most alike, and they understand one another the best. As surprising as it is in retrospect, given how she treated him at first, she's also whose company he enjoys the most, and who he trusts the most...second only to Bright. Letting her down in the way that Bright is describing...it'd be especially crushing.
Rain watches Bright as her stormy grey eyes seem to focus on something far away, neither of them speaking for several minutes. Rain wishes he could say something to console her, but he's never been one for sorry's or condolences...not when he wasn't involved directly. Even if he was willing to, he's sure that the words would feel just as hollow to Bright. So, he decides to remain quiet.
Eventually, Bright is the one to break the morbid silence.
"Hey, Rain...the Crucible..."
Rains eyes widen a bit, turning his gaze to her expectantly. However, he sees that she still has that faraway look in her eyes, her expression and tone heavy. Feeling a pang of concern for her, guessing how she's feeling, he tries to keep his voice lighthearted.
"Oh, that thing? What about it?"
He sees a small smile form on Bright's lips, and she finally turns to look at him. But her eyes are only full of sadness, and her smile lacks genuine warmth. When she responds, her tone is even heavier than it was before.
"Don't die...please..."
Fighting the chilling feelings in his own heart, he flashes her a confident smile, his tone becoming chipper.
"Well...since you asked so nicely..."
*****
Back in his room, Rain and Bright return from his Soul Temple and disconnect from one another. Rising from the floor and stretching with a loud groan, he then smiles and offers his hand to Bright. She raises an eyebrow incredulously at the gesture, but takes his hand nonetheless.
He pulls her to her feet, then studies her face, glad to see that her previously gloomy expression has returned to its stoic default. Deciding to try and lighten the mood, he walks away from her towards his desk. As he does, he speaks over his shoulder in a nonchalant tone.
"You want to enjoy some more tea with me before you go? As thanks for keeping me company and everything else today, I'll even go get us some pastries...your pick, my treat."
As he pours two cups of tea, not waiting for an answer, he hears Bright's voice behind him, her tone mildly amused.
"You're being suspiciously sweet right now, Rain. I hope you don't think that I'm someone who needs to be coddled over something like this. It was uncomfortable, but I'm a big girl...I'll be fine. Besides, I thought you had plans this afternoon? I'd hate to intrude on that totally real and not made-up hot date of yours."
Rain purses his lips in annoyance.
'Yup...she's feeling better...'
Putting on the smile befitting a gentleman as mature as himself, he takes the tea cups in his hands and turns towards Bright. She's now taken a seat on his bed, her legs crossed under her blue knee-length dress, and she's smirking at him. He maintains his polite smile anyway.
"I have no idea what you're talking about, Bright. You're as much of an ice queen as you've ever been, and I wouldn't dream of coddling you. It's true that I have plans with another beautiful woman today, but I still have plenty of time before then. As for why my behavior seems especially pleasant to you right now, that's just my charm finally working its magic. So, please let me know when you're ready to cave and marry me."
He watches her reaction while he walks towards her, expecting her to frown in disapproval and chastise him. However, she lets out a small smile, a touch of warmth reaching her eyes. As he hands her the tea he prepared, she lets out a small chuckle before responding in a slightly teasing tone.
"Ah, I see. I guess your company has been rather nice today. I'll tell you what...survive the Crucible for me, turn twenty, and if you're still interested by then, ask me seriously and maybe I'll consider it."
Rain almost drops his own tea, his eyes going wide and his mouth turning dry. He tries to keep his voice calm as he responds, not letting it sound too shrill, but...he's not completely successful.
"Wait...are you serious? Bright...I'm eighteen. So, I hope you aren't joking, because that's less than two years...I'll definitely remember this."
Bright's face contorts in surprise, her tone becoming a little shrill as well.
"Wait...Rain, you're eighteen!? Since when!? You were seventeen when you first got Marked!"
Remembering that he never told anyone, or even noticed it himself at the time, he looks away from the exasperated Demigod, scratching his cheek sheepishly. His tone becomes a bit embarrassed.
"Oh, right...uhm...my birthday was a few days ago."
Bright stares at him blankly for several seconds, silence settling around them, then her voice becomes exasperated and her expression annoyed.
"Why didn't you tell me it was your birthday!?"
Rain gives her a bewildered look, his voice conveying genuine confusion.
"Wha-...why would I? I mean, honestly, it's not even my real birthday. Since I was abandoned at the orphanage, nobody knows how old I am exactly. It's just a guess. Between that, and the fact that nobody else has really celebrated it before, I don't even realize it until it's passed. Plus, I...uhm...didn't think you really cared about my birthday. I mean, I don't know yours either, right? Actually, come to think of it, how old are you exactly?"
Bright's face twists into an unrestrained scowl.
"H-...how old am I-...what are you implying, you little shit!?"
As Rain's expression morphs into one of horror, confused as to how he managed to make Bright so angry, a loud sound echoes in the room, breaking both of their trains of thought.
KNOCK! KNOCK! KNOCK!
Both of them snap their heads towards the door to his room in confusion, where someone just knocked. Rain makes a puzzled expression.
'Who's that? Ronin? Nik? Or did Tess get the times mixed up?'
Rain glances at his omniwatch as he walks towards the door, and he freezes.
'Shit...'
It's about fifty-five minutes past noon, right around the time he is supposed to meet Tess here. His mind races in confusion. He had a little over an hour left when they were preparing to enter Bright's Soul Temple, and he felt like they'd barely spent any time there. He just assumed it was barely after noon, but...it must have taken longer than he thought.
Forgetting entirely about Bright and their little spat, Rain walks over and opens the door. Just outside the door, as expected, Tess is standing patiently, looking down the hall absentmindedly. Hearing the door, she glances back and locks eyes with Rain. She smiles nervously, tucking a stray piece of her wavy, dark brown hair behind her ear.
"Hey, Rain...I know I'm a touch early. I'm ready to leave whenever you are, though."
Seeing her, Rain is a little taken aback. It's the first time she's been around him without an Academy-issued outfit on. She's wearing a dark green blouse, tucked into jeans that hug her figure tightly, and her dark eyelashes and cherry lips seem to stand out more than usual on her caramel skin. She's always stood out to him as one of the most objectively attractive Marked he's ever seen, especially for a mere Champion, but she's particularly striking today.
Recovering from the shock of her appearance, Rain flashes her an apologetic smile.
"Hi Tess, no worries. Uhm...just give me a couple of minutes and I'll be right out. I'll be quick, I promise."
As soon as he finishes speaking, Tess's face twists into one of shock and confusion. However, she's not looking at him, she's looking over his shoulder into the room. Before Rain can register the strange behavior, she briefly glances back to him, her tone becoming nervous.
"Uhm...Rain...who is this woman?"
Rain turns to follow Tess's gaze over his shoulder, and his eyes widen when he sees Bright behind him. She's leaned against the wall, plainly in view, studying Tess with a curious expression. Seeing that she's been noticed, a wolfish grin finds its way to her face, and her tone becomes amused. Noting the familiar expression, Rain's heart quivers in fear.
"Well, well...I'll be damned. So, Rain, this must be the hot date you mentioned to me earlier. I have to say, she's certainly as beautiful as you described. I wonder...was she told about your birthday?"