The mission node of Tyana Pass on Mars features a special variant of Defence called Mirror Defence, in which the Tenno must defend two different crystals on different planets that are connected through a Void tunnel. Rania's Crystal must be defended from Grineer attackers on Mars, while Belric's Crystal must be defended from Corpus attackers on Venus. Each Defence objective has their own Codex entry when scanned; the Codex entries are listed below.
The crystalised remains of the master foundry operator, Belric.
During the Old War, Belric, Rania, and their guardian warframe Citrine were the last line of defence against a Sentient onslaught upon a strategically important planetoid. In the absence of any eyewitnesses, what happened in those final moments is a matter of speculation and colourful myth.
What is known? A bio-bomb released the Infestation upon the planetoid, halting the Sentient advance and creating a heavily mutated environment. As for Belric and Rania, the evidence suggests they were turned to crystal by Citrine. In her final moments, the warframe chose not to flee but to use the last of her energy to preserve the pair, together, in one final embrace.
The crystalised remains of the celebrated Void engineer Rania.
In an event that has become the stuff of legend, Rania, along with her former husband Belric, were transmuted into crystal by their sworn protector, the warframe Citrine. A merciful end, that saved them from a much worse fate.
Their crystals remained together until the recent past. Smugglers discovered they exhibited some very curious properties; when separated, Rania's crystal remains connected to Belric's crystal via a Void tunnel. How? Perhaps in their final moments, intense emotions deformed the Void substrata, connecting them forever.
Doomed lovers, connected forever. Citrine's last wish.
Belric and Rania Reunited
The Crystal Bastion Collection in the Market contains the Citrine warframe and associated items, including the Orbiter decoration "Belric and Rania Reunited". This decoration can only be obtained by purchasing the collection and is described as "A memory of the lovers, Belric and Rania, preserved in crystal." When placed in the Orbiter and interacted with, an audio recording of the pair's last minute together can be heard. This is not part of the Codex entry, but is included here for completeness.
[Infested growls heard in background throughout.]
[Click, high-pitched whirr.]
Belric: "Detonator's primed. That's it, then."
Rania: "How long do we have?"
Belric: "About a minute. By the time the Sentients get here, this place will be nothing but Infested. Should buy the Seven some time, at least."
Rania: "All those skin-blistering showers, shift after shift, scrubbing every pore. I was never going to let it infect me. And now…."
[ice clinking in glass]
Belric: "A final toast?"
Rania: "Let's die with some sincerity. You were finally free of me, this place. Why didn't you leave, Belric?"
Belric: "Because I never forgot the first time I saw you. [pause] Too sincere?"
[whirr, rapid beeping]
Rania: [deep breath] "I… should have—"
[sound of Citrine's Preserving Shell ability]