Well, in the comics, Black Bolt has to be extremely cautious when communicating. He often uses sign language or very soft whispers to convey his thoughts because his normal voice can cause catastrophic destruction.
Love and loyalty are very common. Their relationship is a central part of Inhuman lore, so fanfictions often explore how deeply they care for each other. For example, stories might show how Medusa stands by Black Bolt even in the toughest of situations.
One common theme is their relationship. Given their status as husband and wife in the Inhumans' lore, many fanfictions explore the depth and complexity of their relationship. It could be about how they support each other in difficult times.
I've heard of 'Black Bolt's Silence and Medusa's Voice' which is a unique take. It plays on the fact that Black Bolt can't speak and Medusa is often his voice in a way. The fanfiction really digs into the psychological aspect of their relationship and how they communicate on a deeper level.
One interesting aspect is the combination of Naruto's existing skills with Black Bolt's power. Naruto is known for his shadow clones and Rasengan, and adding Black Bolt's energy powers would create some really cool and unique jutsus. For example, he could create a Rasengan infused with Black Bolt's power. Another aspect is how it would affect his relationships. His bond with Sasuke might be different as Sasuke would have to adjust to Naruto's newfound strength.
A post - apocalyptic Inhumans setting where Medusa and Black Bolt have to fight to protect the remaining Inhumans. They could face new threats and challenges that test their relationship and leadership skills in a whole new way.