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Some things don't change even across a span of sixty-five million years. Some people are great scientists, some people are great leaders, but people who are both are rare enough to name their own terms.
Madam Ruvaru is one of that rare breed. Originally a physicist employed by the Earth government, she drifted into a second career in administration because she was frequently the only one around who could make the politicians understand the scientists' point of view, and vice versa. By the time of the Great Sleep, she was approaching a well-deserved retirement at the end of a long and spectacularly successful career, but she was recalled to service to lead the Barents Sea shelter.
She was horrified to learn of what had happened to her civilization, but as much as she'd like to restore it to its full glory, she thinks Krayal is a naive idiot who hasn't thought through the implications of what he's doing. Where there's one time-traveling alien, there are bound to be others; and judging by the unguarded comments that she's occasionally managed to coax out of Galen, the others might not take kindly to Krayal blowing up history. And how might they retaliate for his vandalism of the time line? The present situation might not be ideal, but it gives her race a fresh start on highly advantageous terms, and Krayal is throwing that away for a pipedream.
Madam Ruvaru is a member of the humanoid Silurian sub-species seen in the new series. She's a little slow and a little stooped, but her tremendous charisma means that few people notice her physical frailty.
Madam Ruvaru fulfilled her personal and professional goals years ago. Now, all that drives her is a deep-seated sense of responsibility to the people who were entrusted to her care. She wants to see them safe, happy and flourishing so that she can lay down the burden of leadership and enjoy her remaining years in peace.
A dignified, charismatic matriarch, Madam Ruvaru has long since mastered the art of delivering even the most stinging reprimand with soft-voiced courtesy, and phrasing the most absolute command as a polite suggestion. Nobody can ever remember her raising her voice. She rules with such a light touch that it seldom occurs to her subordinates just how completely she's in charge of things.
A member of the three-eyed, terrestrial Silurian subspecies, Dr. Krayal is something of a polymath. A brilliant physicist, he's also a military historian, sculptor, and musical aficionado. Before the Great Sleep, he was the Silurian equivalent of a celebrity academic, popular for his ability to communicate serious science and high culture alike in an engaging, accessible way.
To discover that the rich, diverse heritage that he loved was irretrievably lost was a devastating blow. Art, music, literature, architecture... his entire civilization, all gone forever? The scope of the tragedy was literally too much for him to cope with, and his mind broke under the strain.
The basically ethical individual that he once was isn't entirely gone. He knows that his actions are a personal betrayal of Galen, who saved the lives of everyone in the Shelter and has displayed only generosity and good intentions towards them. More importantly, he knows that his plan, if it works, will unmake the existence of an entire intelligent species. His conscience is uneasy, and his sleep is plagued with guilty nightmares, but he's grimly accepted the burden of responsibility for his own sins in order to serve a greater good - the salvation of his entire race and all its achievements. The future that Galen offers, however comfortable, amounts to life in a glorified refugee camp. It's not enough for him.
Krayal retains some vestiges of his old wit and charm, but they've been eroded by guilt and fanaticism. He's still charismatic, but in a frightening, off-putting way. His speech has become harsh, clipped and to-the-point; he has no time for banter or irrelevant observations. Everything he says and does is subordinated to his goal, and he drives himself and his followers relentlessly to achieve it.
Before the Great Sleep, Krayal wanted to enjoy the best that Silurian art and science could offer, and contribute as much as he could to both. Now, he's become a driven fanatic, determined to prevent the fall of his civilization, no matter what the consequences.
Silurian body language is usually difficult for humans to interpret, but even a human will be able to see that Krayal is under a lot of strain - twitchy, full of nervous energy, and short-tempered. He speaks in brusque, staccato bursts, and avoids looking directly at the people he's talking to.