After the long meeting, Celestia's most faithful students escorted her back to her chamber. They further discussed some details of the plan just among them, then there was time for some idle chat. Finally, the two helped Celestia preparing for the Night. Once she was in bed, they left to reach their room; it was a short walk along a dimly lit corridor dug into the rock, as most of their hideout was, and it wouldn't have taken more than two minutes.
But then Twilight decided to say two simple words. "Thank you."
Sunset Shimmer stopped dead in her tracks, looking at the lavender unicorn for a few awkward seconds. Her eyes were full of gratitude, her smile so earnest. Sunset couldn't help but shake her head and sigh, "You really don't need to, you know?"
Twilight stopped, too, and turned her whole body towards her "I sure do!" And it was clear that she had been waiting for more than she was comfortable with before finally thanking her. "Taking Shiny's place..."
"I didn't do it for you." The orange mare decisively interrupted her peer, almost showing disdain. "It is the most rational way to organize our forces, don't you agree?"
"It is" Twilight nodded energetically, but had a smug smile on her face "And it is impressive that you found it while... No, because you were worried for me!"
Sunset released a second, longer sigh. Her expression had significantly softened: "Can I still try to say that wouldn't be very effective if you spent the whole operation worrying about Shining Armor...?"
"You can. And that would probably be true." A small blush appeared on the purple mare's cheeks "But I know you too well to believe it was the main reason." But then the smile wavered for just a moment, as a related thought invaded her mind "Nopony is as loyal to Celestia as you are, nor to our cause, or to us. And even if the others don't always notice, you are always there to help everypony. Sometimes I still think you are more fit to be second in command than me."
A bit of melancholy was reflected in Sunset's eyes. She took a few moments to collect her thoughts before answering: "I used to think the same. I even used to be a bit jealous of you..." Twilight was younger and had been Celestia's student for two years less then her. And yet, sometimes she felt that Celestia favoured her. When she decided for who her second in command would be, it felt like a confirmation of her worse fears. It was painful, as her teacher was everything to her... But she was now over it "Then I thought... How can I be jealous of such a cute junior?" With a quick motion, she got closer to her friend wrapping her in a warm hug. When, after a few moments, she turned her head to better see twilight's face, she knew she wasn't satisfied by that answer. For the third time, she sighed. "I trust Celestia's decision. I'm sure she has plans for both of us." That was what everything boiled down to. "And honestly, even if I had the title I would very much do what I do now." It would have been nice, wouldn't it? It would have meant that "And the same goes for you. I like Moondancer, but she isn't a leader. It's clear that the research team depends on you more than on her... And if it's Applejack or Shining, they would still listen to your every advice."
"You are probably right..." Now Twilight, a bit reassured, could fully reciprocate the hug. "But I'm trying to have Moondancer be more assertive, you know? She can still become a great leader!"
"See? That's what a leader would do!" Both smiled, and Sunset even giggled a bit. Then, slowly, she started to pull out from the hug. To her surprise, Twilight didn't let her go.
"I am still worried, though." She whispered, with her cheek on the other mare's neck, her lips close to her ears "Not for my brother, but for my sister!" A few moments of pause, during which Sunset blushed. "I know how much you hate Discord, but don't do anything crazy. Please..."
That was a first, and Sunset was speechless for a few moments. She considered Twilight to be much more than just a fellow student, and sister was probably the right word. The fact she felt the same was so unexpected and so wonderful, that even against her better judgement she couldn't but yield "I won't". Her arms, again, went to squeeze her fellow student. Her friend. Her sister.
"Thank you."
...
"Still, don't think you are safe." Her voice was now a teasing one, with a note of Irony, but the comment was nothing to laugh at. "If the plan fails, we are all bucked!"
"I-I know!" Twilight was not a mare to underestimate the situation at hand. Or any situation. But... "But not now. Don't ruin the moment!"
"Sorry, sorry!" And another, heartfelt giggle resounded in the tunnel. Then she just basked in the other mare's warmth for a bit more. the next day they would both have departed, getting started on their missions. They didn't know when, and even if, they would have had another chance to hug like that, so they both silently agreed it was best to enjoy it as long as they could.