When Kairi had wandered into the secret cave, tracing the paupu drawings with her fingers, she had shed tears. She did not know where her friends were; Sora's location was completely unknown. She missed them dearly, and she wanted them to come back. Her tears had been tears of loneliness.
When Sora had wandered into the secret cave, tracing the paupu drawings with his fingers, he had shed tears. He had brought Riku back. Kairi had been waiting for them. They were all back together on their tiny island home. He had missed them dearly. Now they were back. His tears had been tears of happiness.
When Riku had wandered into the secret cave, tracing the paupu drawings with his fingers, he had shed tears. Sora was just outside, eagerly trying to carve a wooden sword in the shape of a keyblade for the baby brother he'd just learned he had. Kairi was hanging about, cooing at the little brown-haired 14-month-old as he tottled about, desperately trying to keep on his feet and move towards her. He had missed them dearly, and now they were together again. His tears had been tears of loneliness.
Even now, they were all together again. Sora loved both of them, Kairi loved both of them, Riku loved both of them. But Riku felt the drawing told the truth after all.
He still wasn't part of their little paupu world.