3 Mystery of Serenity and Nehelenia

She sees another galaxy, one that is long dead in her own world and time, and Usagi knows she has been given the gift of knowledge about the life of others. So, she lets the dream take over and fades deeper into it…

Serenity, born to guard and harness the power of the white moon that protects earth in a far off galaxy.
Nehelenia, born to guard and harness the power of the dark moon in the galaxy they both come from.
This they have been told since they were both old enough to start grasping the idea of their respective powers. And it never gets easier. They were born together, they share a bond that nothing and no one can break. But they day and time is here, and they spend their last time together by the old tree in the garden of the house they have grown up in with their parents. They don't say anything, for there are no words, but their minds slither together, savour each detail from the others, to keep it locked up in a precious corner of their hearts.
Serenity, the one that leaves, settles in on earth's white moon with ease, for she is calm and serene as her name, and in time gathers many around her that are happy to share the light she gives off.
Nehelenia, the one that stays, settles on the dark moon with a heart that is heavy, for she has always been hasty and needy for more. She draws people around her as well, and they share her need for more.
Years passes by, and the sisters are busy on their respective moon, content in their ways.
Unknown to them, because time has changed them both so much, their bond is now frail and can easily break.
Nehelenia watches through her mirror, sees her sister bear a child, gather girls to guard the child, to protect the galaxy Serenity is in, and a small sliver of her heart darkens in jealousy even as she is happy for her sister.
Serenity sees, through the pool that captures the light form within the moon itself, how Nehelenia fails to have a child, but she surrounds herself with people who adore her because of how beautiful she is, due to the power she radiates, and Serenity is glad and wishes more happiness for her sister.
More years fly by. The sisters have not seen each other, nor had contact in any way. Their bond is now a thin thread, although they do not know it.
One day, near dawn, the planets of their respective galaxies shimmer, form a straight line that coexist at the exact same time, and a bridge opens, connecting both moons. In the middle of the bridge is a void where dark and light meet. A silent nothing. Serenity comes from the white moon with silver flowers in a basket. Nehelenia walks form the dark moon with glimmering dark rocks in a basket. The sisters meet in the void, and what transpires there is unknown to all but them. When they leave, the each carry the gift from the other, hard eyes and a veil of sad determination.
Serenity seals of her end of the bridge for all eternity, shrouding it in mist of shimmering moonlight that no one can pass through.
Nehelenia rises dark spikes that glimmer on her end of the bridge, spikes that hinder anyone that may wish to enter.
Their bond breaks.

Usagi wakes up with sorrow and confusion in her heart. What happened and how is it relevant to what Nehelenia is doing now? Usagi looks out through her window on the new moon that hangs in the sky. It holds no answers for her. She plays with her hair and ponders until dawn approaches, and then she pulls her hair into odangos, picks out a dress to wear and heads over to Rei to see if the sacred fire can provide help.