The dormant Ruby is kept in observation for a week - the week Allura and Coran spend hidden in Sol's asteroid belt, waiting for the Paladins to return from their brief visit to Earth - before they give up on her. They don't learn much from the actual gemstone, except for the fact that, while its physical appearance may not differ at all from a genuine precious stone, its atomic structure is far too advanced for even the Castle's AI to understand. It bugs Coran and Allura for longer than they'd be willing to admit, but they're eventually forced to declare that the Gems must have developed their own, unknowable kind of magic. The Ruby is kept in one of the Castle's many spare rooms, and eventually, forgotten.
Allura is kidnapped and rescued, Emperor Zarkon presumably dies in a climactic duel with Voltron, the witch Haggar is discovered to be a traitor to Altea, Shiro goes missing in action, and the Galran Prince, Lotor, enacts a temporary truce with the fledgling Voltron Coalition before anyone in the Castle thinks of the Gem again. It's kind of crappy of them, for sure, considering they're ferrying around a sentient being like it's just part of their cargo, but the Ruby's gemstone hasn't done anything since they reluctantly kept it after First Contact with her race, and honestly, they've had a few too many universe-altering events to worry about in the meantime.
It's quite a shock, then, when the Castle's intruder alarms go off in the middle of the night cycle, prompting the Paladins to bolt awake, bayards blazing, only to find a panicking little Gem running around the training room in a panic.
"Oh my gosh, is she trapped in the…"
"Yup." -says Pidge, as the Ruby slams into one of the invisible maze's walls for the third time in a row. Lance snorts, which isn't very nice, but way more honest than Pidge's attempt at a neutral expression.
The Ruby doesn't seem to notice them, instead punching and screaming at air in frustration. Allura rushes into the room, in full Pink Paladin regalia - regardless of the fact that none of the Lions have responded to her yet, she's been a huge help with ground missions - and frowns at the scene.
"Why are you all just staring at her?" -she asks, indignant. "Coran, lower the walls."
"But Princess, the Ruby's broken through no less than a dozen blast doors!" -he protests through the speakers.
Allura cringes a bit, but puts her foot down. Pidge can't even hide how impressed she is by Coran's statement, considering the Castle's internal reinforcements are supposed to be just about as durable as its external hull plating. "She's just confused, I'm sure. She did just wake up in an alien ship."
Coran seems to hesitate, but ultimately complies, just in time for the Ruby to try slamming into the energy wall for the umpteenth time. She, of course, cartoonishly runs past the missing maze and straight into a nearby bulkhead, leaving a perfectly Ruby-shaped imprint on the Altean alloy.
The Ruby groans, dazed from the unexpected crash. Pidge finally gets a good look at her: her gemstone remains on her right cheek, and her body and hair are unchanged from the form she remembers, but the uniform she wears is slightly different. The Yellow Diamond is still there, but it's on her back, now. The red, black, and maroon also seem...softer, less harshly contrasting.
Allura slowly approaches her. It makes the most sense, given her Altean strength and durability. Pidge isn't willing to bet on who's the strongest, but Allura can probably take a hit or two, giving the Paladins time to bring their bayards to bear.
"Are you ok?" -the Princess asks, softly.
The Ruby blinks, hesitant. "Yeah. Are you...one of hers? I can't feel your gemstone."
Everyone is confused by this. "I'm not a Gem." -Allura says, gently, taking off her helmet. "I'm Princess Allura, of Altea. Pink Paladin of Voltron."
Cheek Ruby finally notices the others behind her. "Ohhh, I remember you guys! Sorry, I just thought...with the pink, and everything…" -she says, embarrassed.
"That's ok." -Allura reassures her, even though none of them have any idea of what she's saying. "I imagine you're very confused, so I'll bring you up to speed: you're aboard the Castle of Lions, our home and main base of operations for the Voltron Coalition. We took you after the battle as a favor to one of your friends, but...well, it's been quite some time since then. We honestly didn't expect you to ever reform."
The Ruby's eyes do the weirdest thing then: they briefly become white and cyan, and something resembling data - Gem code, Pidge would wager - streams down their circumference. It only lasts a second, after which she gapes, holding her forehead as if experiencing a headache. "Oh my stars! But I wasn't trying to hold off reforming! How did it take this long?"
Pidge frowns, suspicious. "Why would you wanna wait to come back to life?"
She fidgets. "I...nevermind. I need to get back to my post immediately." -she says, abruptly.
"Yeah, that's gonna be a problem." -Lance says. "We're, like, on the other side of the universe."
The poor Gem looks like she might faint at this. "What!? But my Hessonite needs me!" -she panickedly shouts. "Please, Princess Allura, I need to go back to the nearest Gem colony as soon as possible!"
Like Lance said, it's a problem; it's not just the distance - which Altean wormholes can make relatively short work of, at Allura's expense - but the fact that they're at a crucial juncture in their fight against the Galra Empire. Prince Lotor may not be, at least on the surface, the power-hungry despot his father was, but he's not exactly a friend, either. He's brazenly taking advantage of the fact that Voltron cannot be formed without the Black Lion to enforce this illusion of peace, effectively grinding the liberation movement to a halt until Shiro - or, more realistically, another Black Paladin - is found. Lotor's buying time to decide where to take his Empire, and charming though he may be, it's entirely possible that he'll continue in his father's footsteps.
"I'm sorry, Ruby." -the Princess says. "It's going to have to wait a bit."
"No, it's not. I can take her." -Pidge finds herself saying. Everyone is surprised at this, herself included. A part of her mind is sensibly yelling at her about how bad this idea-in-progress of hers is, but she shuts it up.
Lance frowns. "Where did that come from?"
The Holt side of the family tree, she snarks to herself. Pidge crosses her arms; her idea may be impulsive, but damned if she's not gonna argue the heck out of it. "I'm the logical choice, guys. I'm no good at all the diplomatic stuff we've been doing, and we haven't fought anyone in weeks. Plus, I'm sick of getting no progress on the Galra tracking algorithm. I could use the change of scenery."
"Still, we shouldn't split the team up." -Keith says. "What if Lotor decides to stop playing nice? What if the Galra Commanders get tired of peace?"
"Well, it's not like Voltron's gonna rush out of the Castle anytime soon, anyway." -she counters. It's a bit of a low blow, but they all know it to be true. "You guys can handle it, I know you can. Plus, the Coalition is already shaping up to be a decent fighting force, so you wouldn't be by yourselves in a fight."
Pidge briefly wonders how this discussion would go with Shiro around. Allura refuses to take up his well-earned mantle, and Keith tries his best, but he's not quite ready to be the leader Shiro wanted him to be.
Wants. Gotta keep up the optimism.
"I mean, it's not ideal, but this is the best time for Pidge to zip to the Milky Way and back." -Hunk argues, then looks at her. "The Galra aren't patrolling the hyperlanes right now, so you'd make the whole trip in...what, a week?"
Pidge does some quick FTL calculations in her head. "Less, if I cut across their holdover sectors."
"It's far too risky." -Allura says. "A Lion on its own may be too tempting a target for even the most disciplined of Galra."
"So she doesn't go alone." -Lance says. "I'll go with her, make them think twice."
Pidge rolls her eyes. "I don't need an escort to go from point A to point B."
"How about a wingman, then?" -he says, shrugging. He pointedly glances at the expectant Ruby, then back at her. The Paladins aren't quite at the 'mutual telepathy' stage of their development as a team, not when said team is now so glaringly incomplete, but she gets the idea anyway; Lance isn't so much worried about Pidge and Green's ability to handle a few greedy Galra, as he is about the idea of her trekking solo across the universe with a being they know almost nothing about.
It's still kind of annoying, but she'll let it slide because, yeah, it's probably the smart way to go about this.
"Fine." -she allows. "Grab some supplies while I plot us a course."
The Ruby tackle-hugs her waist. It's kind of crushing her hip bones a little, but the Ruby's too cute to push away. "Oh, thank you, thank you, thank you!" -she says. "It's too bad you're not a Gem. My Commander might've thanked you with your very own Pearl!"