Hi, so I don't even ship Deceitmus, but I wrote this so enjoy!
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   Deceit and Remus probably know each other better than any other side. They know what the other will say before it comes out of their mouth and what they are thinking about at any given moment. This may be surprising, seeing how almost everything Deceit says is a lie and Remus is nearly unpredictable to most. But when you spend so much time trapped together in such a dreary place, the line between one side and another becomes blurred, nearly gone. Around their second year together they started wearing each others clothes. It wasn't on purpose, it was just convenient. Their signature yellow and green became a mixed collage of the two colors.
   Had Virgil not shown up when he did, they probably would have become one. Virgil brought drama and change. Virgil and Remus did not get along while Deceit became naturally attracted to him. Remus lost his other half once again. This only fueled Remus however, with no one to distract him and Thomas's growing stress, he became louder. The dreary place Deceit and Remus had come to know expanded and and gained more rooms. Remus began to... annoy Virgil; always popping up when he hated the most. Virgil hated Remus and Deceit suddenly avoided Remus like the plague. They both, Remus and Deceit that is, cried at night. The difference was Deceit had Virgil who... comforted him. It was never a healthy relationship, they consumed each other rather than possessed each other equally as Deceit and Remus had.
   Remus often reminisced his time with Deceit, and with his power as Creativity he often created a fairly accurate clone of Deceit. He talked, and played, and danced with this beautiful clone. God, he missed his Deceit... When one day Virgil heard Remus talking to the clone in his room, he burst in and verbalized his disgust. "What!? What the fuck are you doing to some doll version of him!? Sicko!" Remus was truly frightened of Virgil for the first time.
Needless to say, Deceit was informed quite soon after. Deceit found Remus bruised and in tears by himself in the darkest corner of Thomas's mind. Virgil didn't mention to him Remus was hurt...
"Rem? What happened?"
   Remus whimpered and cried in such a heartbroken way Deceit felt himself shatter. Before he knew it he was on his knees in front of the friend he forgot, tears running down his own face. "Ssssorry... I am ssso sssorry...." Deceit sobbed and crawled to Remus, who laid curled in a fetal position. How could he leave someone who meant so much to him, someone who practically WAS him? Remus simply opened his arms and legs and like nothing had ever separated them, they blended together. They made such a pretty chartreuse together.
   Virgil watched from afar and scoffed. Anxiety can't help but sabotage any good thing it touches, in any way possible, regardless of the side's feelings. It was what he was after all. Virgil wished he could join them, he wished he could love Remus a much as Deceit did and they could all love each other. But it was not possible. So, Virgil went directly to his roots. Fight or flight? He asked himself. Deceit will never trust him again...  Flight it was.
   Virgil then attempted and succeeded at something Remus and Deceit never even thought to do. Escape and become known to Thomas. Virgil unknowingly set off a chain of events Thomas and his sides could not escape from. Foolish, foolish, Virgil. It is all his fault.