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Original Description:
 
It was after midnight when Rarity woke up in my Royal Equestria Security Force (RESF) dreamscape. Unfortunately even being half awake Rarity was familiar with what was going on.  
Her and Coco were lying in bed together. Coco was pressed close against Rarity’s chest; the earth pony’s muzzle was buried into her breasts. Under most circumstances this would be an adorable, intimate moment, but Rarity could feel the mare’s shivering and the rapid muscles twitches. Coco’s breath was short and rapid.  
Rarity continued to gently hold Coco. The Element of Generosity had seen this before. A few seconds later the sleeping mare started muttering. Most of the words were incoherent, but Rarity started catching snippets of words.  
“No. no.” A what followed was a collection of unintelligent mutterings. Then Rarity heard. “Get back into the tunnel. What are you doing? Stop!”  
Tears started trickling down Coco’s sleeping cheeks. The shivers grew more severe. Coco never seem to have nightmares about the assignments since she’d joined RESF, but she often had them about those weeks in Manehattan when the portal had opened for the first time. At that time Coco had just been a confused, scared, and desperate young mare struggling to survive in a world gone mad.  
Rarity and Coco had discussed it on numerous occasions, and Princess Luna had through the Dream Realm counseled mare on how to deal with the nightmare when they came. But some nights the mare couldn’t keep the monsters in bay.  
The white unicorn started gently stroking Coco’s mane. At the same time she began cooing softly and making various nonverbal sounds of comfort. Over the next minute the earth pony’s shaking subsided and calm settled over her face. Rarity slowly lowered her head and kissed Coco onto top of her’s. Then she drifted off to sleep again herself.