Keep in mind that this starts off as Cross/Dream! :0
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They were huddled closely in the vast white space that was Cross's home. Cross sighed lightly as Dream gradually dozed off to sleep. Cross couldn't help but smile being so close to the god of positive feelings, his presence alone would make anyone endlessly happy.
Back then, though, things were different. Back then, Dream didn't trust him whatsoever. Back then, Dream kept his guard up towards him. Back then, Dream hated Cross.
Cross changed that. He spent a long time aiding Dream in errands; he even made himself useful in missions. He did so many things, and spent so much time, just for this small moment of affection. Just for Dream to lower his bow and believe Cross when he assured that he loved him. He spent so much effort for this.
When Cross heard Dream's quiet, even breathing, he carefully laid Dream on the floor. Staring down at the sleeping guardian, he could really see all the little details. He was so brave, so helpless, so...
Stupid.
Cross swiftly unleashed his bright-red knife, he aimed it right towards Dream's abdomen, he... hesitated. Is this right? Dream had shown him so many beautiful places; he met so many kind people. He even got to talk things through with Ink because of Dream's encouragement. Dream changed him. Was he really going to throw all of this away?
...
What was he thinking? Of course he will. He'll do anything to make Nightmare happy.
Just like that, he heaved the large knife all high and mighty. He faltered as Dream began to stir, that can't be good. He paused for a second.
Before Dream could fully wake up, he jabbed his knife through Dream's torso. His face of pure shock would be in Cross's mind as the glitches quickly covered the small tears that edged in Dream's eyes. His stiffed body quickly limped as if he died. But no, of course Cross wouldn't kill him. That's not what he requested.
Cross turned towards the familiar sound of someone teleporting, the one-eyed guardian of negativity. "It was about time you took him down," Nightmare scoffed. "Aaww, were you getting a little jeaaalous?~" Cross teased. Nightmare's only response to Cross's comment was the classic rolling of his eye as he wrapped his arm around Cross to pull him closer.