Writers can create tension through the reactions of other characters. If Gray starts acting strange because of the mind control, and his friends in Fairy Tail are worried but can't figure out what's wrong right away, that builds tension. They might try different things to snap him out of it, but keep failing, which keeps the readers on edge.
By making the source of the mind control elusive. If the readers don't know who or what is controlling Gray, it creates a sense of mystery and tension. For example, it could be a shadowy figure that only appears briefly in the story at first.
Writers can create tension by having the character who drank the love potion be in a relationship already. So, they are torn between their real love and the artificial love caused by the potion.
A frequent theme is the mystery behind the mind control. Who is controlling Gray? Is it a new villain? Or some old enemy with a new power? Figuring this out can be a major part of the fanfiction. And sometimes, it can also involve the use of Gray's unique magic in unexpected ways while he is mind - controlled, like his ice - make magic being used for more sinister purposes.
Firstly, they should have a good understanding of the original Fairy Tail universe. This includes its magic system, characters, and the relationships between them. Then, when creating reincarnation scenarios, give the characters unique backstories related to their past lives. For example, a character might have been a great mage in a past life but lost all their power in this life and has to regain it. Also, introduce new and interesting plot twists. Maybe the reason for reincarnation is not what it seems at first.
By using descriptive language about the attack. If the writer vividly describes the attacker's menacing appearance, like 'The dark - cloaked figure loomed over Hermione, its eyes glowing red as it raised its wand menacingly', it makes the situation seem more dire. Also, showing Hermione's fear and vulnerability, such as her hands shaking as she tries to reach for her wand, adds to the tension.
One common theme is the struggle for freedom. When characters are under mind control, they fight against the external force controlling them. Another is the exploration of trust. Mind control can make characters question who they can trust within the guild.
Another way is to have the character's upset tummy be a result of something they did wrong, like stealing food and now they are suffering the consequences. This creates an internal conflict within the character as they deal with both the physical pain and their guilt, which adds to the overall tension of the fanfiction.
One way is through the reactions of the other characters. If the village leaders start to question whether Naruto can still be a useful ninja, it creates tension. And if his friends are divided on how to help him, that also adds to it. Another method is by introducing new threats that specifically target Naruto because of his weakened state due to his breathing problem. Maybe there's a group that wants to take advantage of his vulnerability.
Writers can create tension by having the fungal infection spread quickly. If it starts infecting more and more characters at a rapid pace, the remaining characters will feel pressured to find a solution fast. For example, if a whole village gets infected overnight, the RWBY team will be in a race against time.
Sure. One popular 'fairy tail mind control fanfiction' is 'The Enchanted Minds in Fairy Tail'. It has an interesting plot where a mysterious magic starts to affect the minds of the Fairy Tail members in unexpected ways.
Another way is through the description of Taehyung's own state. If he's in pain but trying to be strong, or if he's confused and hurt by the situation, it makes the readers feel for him. The writers might also introduce some obstacles in his recovery process, like a lack of proper medical facilities or some internal conflicts within the group that delay his getting better. This all serves to create and maintain tension throughout the fanfiction.