One consequence could be extreme physical exhaustion. Just like in the original series, opening the gates takes a toll on the body. So Naruto might find himself unable to move or fight for a while after opening the gates in fanfiction.
One interesting scenario could be Naruto opening the gates in a new and unexpected way, perhaps using a combination of his Sage Mode and the gate - opening technique to achieve a super - powered state. Another could be him teaching others how to open the gates more effectively, like training Sakura to open the gates for enhanced physical strength in combat.
Rock Lee is depicted as a highly determined and hardworking character in the manga. He doesn't have natural talents but makes up for it with his perseverance.
Rock Lee has a sad story of constantly facing challenges due to his inability to use ninjutsu at first. He was often looked down upon by his peers. But he didn't give up. He trained extremely hard, pushing his body to the limits with his taijutsu. For example, his weights that he always carried around were a symbol of his self - imposed hardship. All he wanted was to prove himself as a great ninja in his own way.
I don't really know if the 'rock lee ghost story' is popular. It could be popular within a niche community of fans who are really into Rock Lee and also interested in ghost stories. But if it's not widely known outside of that small group, then it's not very popular in general.
Another plotline might involve Naruto opening the inner gates during a crucial battle where he is severely outmatched. His use of this extreme power could turn the tide of the battle and also earn him new respect from his enemies. He could also face the consequences of using such a powerful and dangerous technique, like dealing with the extreme physical strain it causes in new and unexpected ways.
In certain fanfictions, Jiraiya could be involved. He might be the one who discovers Naruto's potential to open the gates in a unique way. He could train Naruto further, teaching him how to combine the power from opening the gates with his other jutsu. Also, Hinata could be around, cheering Naruto on when he shows off his gate - opening skills during a battle or a training session.
A really interesting 'Naruto Rock Lee Fanfiction' is 'Lee's Hidden Potential'. In this story, Rock Lee discovers a new form of power within himself that is not related to the normal chakra system. It's a fresh take on his character, and it explores how he adapts to this new power while still staying true to his original values of hard work and perseverance.