Dean ran a hand through his short, messy hair and grabbed Cas by the hips, backing him closer. He wrapped his arms around Cas's waist and kissed his neck. Cas yawned and turned his head to accept Dean's lips against his own. He knew.
Cas curled into his side later that night, pulling the blankets around their tightly woven forms. Dean groaned and rolled away. He knew.
Dean threaded their fingers together under the table the next morning. Sam was oblivious. Cas drooped. He knew.
"Cas, oh God," Dean panted, grinding into him. The denim layers provided ample friction and Castiel was also out of breath. The two fell asleep on opposite sides of the bed. He knew.
Dean swallowed and fumbled for Cas's fingers while they were walking to the Impala. He held them all the way to the Motel 6 they were staying at. Cas sighed at the loss. He knew.
Cas was pressed up against the wall, yet again. Dean was tonguing his mouth, desperate for taste. The scent of sweat and musk filled the small room. He knew.
Sam commented on their odd behavior and Dean recoiled for three days. He even slept with Sam. He knew.