A/N: As far as I know, Makoto isn't astraphobic in canon, but I don't think it's too much of a stretch, given his fear of storms at sea, and how easily frightened he was in the first episode.
"Haru, you don't need to stay here," Makoto said sweetly.
Haruka looked blankly at his boyfriend. "It makes you feel better," he replied.
His point was quickly proven when an especially loud thunderclap made Makoto whimer and burrow against Haruka and into the couch cushions.
As luck would have it, Makoto's younger brother chose that exact moment to appear as if out of nowhere. "Haruka!" he cried. "Are you going to stay here all night?"
The two high school boys replied at once. "Shouldn't you be in bed?" "If I have to."
As the younger boy grinned with happiness at Haruka's answer, Makoto turned in mild surprise. "You would?" he asked.
"I'm lonely at home anyway," Haruka said. "It's nice to be with you."
Makoto blinked away the wet sheen that had come over his eyes. "Thanks, Haru," he whispered. As another thunderclap came, he startled again, but immediately afterward fell comfortably against Haruka.
It was a good place to fall.