If Ruby was the Sister who eeriely resembled Mother, Opal was the one who actually wanted to. Severe, pale and chill, Opal wasn't the first choice for anyone's best friend at Carramba. However, she was obviously dedicated to her sisters and their task, and was quite notable as an unattainable 'goal' for some of the guys.
She could seem warm, gentle and loving. Of course, she could seem almost anything she put her mind to. But really the only thing she did, genuinely, care about was getting her sisters home in one unit and getting the Combine off their planet. She was fierce, but in a way that wasn't so physical as Carmine or Crimson. If Indigo was their visible leader, Opal was the one that Indigo deferred to in order to get things done. Opal knew who was where, she had an innate sense of distance and how things were going.
Perhaps it was that her own communication link to her sisters was almost always passively "on", rather than only on when concentrated upon. With her watching, the others felt more safe, more comfortable, more like a unit. Without that - which had happened only two or three times in their short lives - they often began to dissolve into disagreeable cliques. Opal sought to avoid that at all costs.
While she couldn't actually speak every language encountered on their earth or on Twoarth, Opal understood the meaning behind most things, and managed to keep the snide remarks by people to a minimum with a caustic glare or a tiny mental nudge. Or a big mental nudge. Sometimes it took more than a flash of anger to keep the idiots at bay.
Even though her Public Relations teacher didn't particularly care for Opal, Cybil Qeats had to admit that she was quite good at the job. Putting in just exactly the right word of encouragement, wording requests the right way. Those were the hallmarks of a good organizational mind.
Ms Prescott actually enjoyed Opal's presence in her Speech class, as she was able to rattle off accents like nobody's business. Opal could tell the slight but present changes to inflection that were needed when speaking to a Fursider or their Human counterpart. And more: she could tell the emotions displayed even when they weren't apparent in the words.
Of course she absolutely excelled at her Linguistics course, but also in her Universal History class. Both subjects could be tucked away into the collective of her sisters' minds easily.
Cartography and Astrogation were things that, while she was never expected to actually go out and pilot a ship or craft, Opal would certainly be able to navigate one with great ease. Once more, as well, this facet of her education blended seamlessly with that of her sisters, and they all felt more 'at home' whenever they knew just exactly where they were.
The Exotic Team Sports class gave Opal the chance to show off her play-calling - even when she started to show some actual excitement about the games she officiated, Opal's play by play was accurate and well-timed. She was never going to be the most physical of the group, so at least that could keep her in the action.
And then there was the Dragon Care class, which obviously filled her with pride. They were such amazing, magnificent creatures. And unlike, say, Cobalt, Opal deeply appreciated the safety gear that they learned how to use when mounting, assisting, or even cleaning up after the great dragons. After all she didn't really want to get all that dirty.
It was through Opal that Indigo knew when she was needed to bond the others together again. Little pings of communication, easily traded between the two of them, not so lightly spread among the rest. If Indigo needed to keep a secret, Opal would be the one to do it. Her control over the network of their minds was far more subtle than Indigo's, while she didn't really manipulate them, Opal definitely could sway them as a group into ever more impressive results.
Imagine what they could all do with dragons. Just. Imagine.