You are their son.

Dazai is watching over you while you play with a plushie. At some point you got tired of playing with the plushie and started crawling, slowly getting up. Dazai's eyes widened in surprise. "Kunikida, come here!" Dazai called for his husband.

"What-" Kunikida entered the room, looking at you and Dazai who was tearing up. "My baby is walking!" Dazai said, pointing at you.

"Calm down." Kunikida said to Dazai, but also crying inside.