One possible reason could be that he is lonely. In many fanfictions, Naruto is often ostracized as a baby due to the Nine - Tails inside him. He might be crying because he feels the lack of a warm, loving presence around him.
They can describe his physical state. For example, 'Baby Naruto's face was red as he wailed, his tiny fists clenched tightly.' This gives a vivid image of how he looks while crying.
Kakashi would probably first check if Naruto is hungry or needs a diaper change. If that's not the case, he might hold Naruto close and gently rock him while humming a soft tune.
I'm not entirely sure specifically what 'baby tails crying fanfiction' is about as it could be very unique. It might involve characters with baby - like tails in a situation that makes them cry, perhaps in a fictional world created by the author's imagination.
Sakura could be the one to find him crying. She has known Naruto for a long time and they are comrades. If Naruto is in a vulnerable state, she might stumble upon him.
It could be the result of Naruto's own inner demons. Maybe he discovers some dark secret about his past, like his parents being involved in something he can't accept. This self - realization could be so traumatic that it makes him cry blood as he struggles to come to terms with it.
One common theme could be vulnerability. If baby Bella is crying, it might show her in a state of being exposed and fragile. Another theme could be the need for protection.
To make it engaging, add some mystery. Let the readers wonder why the baby boy is so confused. Is it something supernatural? In a horror - themed fanfiction, perhaps there are unseen forces that are causing his distress. His crying could be a signal that something bad is about to happen. You can also use dialogue, even if it's just the baby boy making incoherent noises at first, and then gradually as the story progresses, he might start to communicate in some strange way.
Once upon a time, there was a couple who moved into an old, creaky house. One night, they heard a baby crying. They thought it was a neighbor's baby at first. But as they followed the sound, it led them to an abandoned attic. In the attic, there was an old, dusty crib with a tattered doll in it that looked like a baby. The crying got louder and more eerie. They ran out of the attic in fear and never went back again.