Itachi insisted that his favorite season was summer, even if he can't bask under the sun for too long. He got lightheaded too easily from the heat - a symptom of his illness - so Kisame has to stay with him, under the shade of an umbrella, acting as his personal lifeguard. From here, they can safely watch people as they come and go like the waves. Life was short and only a few people stayed on the water even when the seascapes changed from a brilliant sapphire to misty blue.
Kisame stayed with Itachi, because he was his partner and someone needed to take care of him. He couldn't find a reason for Itachi to appreciate the summer, though, if it was making Itachi so dizzy and sweaty. When he asked Itachi for the reason, the Uchiha simply smiled at him, as if Kisame was falling behind a really obvious riddle.
When the sun began to sink, Itachi got up from their spot and put sunblock on Kisame's back, because apparently, sharks still needed protection from ultraviolet rays. Kisame did the same, purposely slathering Itachi's back with the cream.
Kisame rushed into the water first. He reached the depths easily, and extended a hand towards Itachi to join him. Itachi dipped slowly, feeling the temperature, and stopped when he saw something in the water.
"Itachi-san, what's the matter?"
Itachi smiled at him yet again, genuine and secure. It was the kind that was reserved for special people, and Kisame was one of those lucky few. "Your friends are here," Itachi said, pointing at a school of colorful fish dancing around his knees.
Kisame grinned. "I told them I'd be bringing someone over, so they got pretty excited."
Itachi snorted fondly and went deeper into the water until he reached Kisame. They were the only ones left on the beach; most of the people had returned to land, giving Itachi and Kisame privacy.
Purple-colored skies surrounded the orange sun as it shrunk down the horizon. The waves were warm from the afternoon heat and gently rocked them back and forth. Kisame held Itachi close, and it was at that moment that he understood why Itachi liked the summer so much.