Well, if Harry is given too much Veritaserum in fanfic, one consequence could be that he loses control over his own narrative. Since Veritaserum forces you to tell the truth, he may end up sharing things that are not only personal but also strategic in the fight against Voldemort or other enemies. This could disrupt plans and alliances. Also, it might change the relationships around him. His friends might be shocked or disappointed by some of the things he reveals, and his enemies might gain an upper hand. It could lead to a very different storyline compared to the original plot.
The overuse of Veritaserum on Harry in fanfic could have several outcomes. Firstly, his mental state could be affected. Constantly being forced to speak the truth without control can be mentally exhausting and might lead to psychological distress. Secondly, it could have a big impact on the plot. All the secrets he spills could cause chaos in the wizarding community. Maybe some dark secrets about Hogwarts or the Ministry of Magic come to light, which could lead to power struggles and changes in the social structure. And his relationships would surely be tested. His friends may not trust him as much if he reveals things they didn't expect, and his enemies would try to take advantage of the situation.
His relationships would likely be strained. Since he can't control what he says, he might say things that hurt his friends' feelings. For example, he could blurt out that he thought Ron's Quidditch skills weren't as good as he pretended. This would surely cause some friction between them.
Well, if Harry is given too much Veritaserum in this fanfic, he might start revealing all kinds of secrets. He could disclose things about his friends that he wouldn't normally tell, like Hermione's insecurities or Ron's hidden fears. It could also lead to him accidentally spilling information about the Order of the Phoenix's plans, which would put everyone in danger.
It could start with someone having a malicious intent towards Harry. They might slip him the Veritaserum in a drink or some other way. Then, as he starts to spill the truth, it creates a chain reaction. People around him start to react to the things he reveals. Maybe his friends try to protect him from further exposure, while his enemies try to get more information out of him.
Well, in a fanfic, if Harry is given Veritaserum, he might reveal all kinds of secrets. Maybe he'd spill the beans about his true feelings for his friends, like how much he really trusts Hermione and Ron. He could also disclose some hidden details about his battles with Voldemort, things that he's kept to himself because of fear or just not having the right moment to share.
One major consequence could be that Harry reveals his connection to Sirius Black. If Umbridge gets to know about this through the Veritaserum, she could use it as a weapon against Harry. She might try to capture Sirius or use his existence as a way to blackmail Harry into following her every order. Also, Harry could end up revealing the details of how he has been learning magic outside of the school curriculum, which would be a huge violation in Umbridge's eyes.
One possible consequence could be that Harry reveals some deep - hidden secrets. For example, his true feelings about his friends or his fears regarding Voldemort. Since Veritaserum forces the drinker to tell the truth, Harry might disclose information that he has been keeping to himself, which could then change the way Snape views him or the actions he takes in relation to Harry.
Well, if Umbridge uses Veritaserum on Harry in a fanfic, it depends on how the author writes it. Some fanfic writers might have Harry spill out information about the Order of the Phoenix, which could put the whole organization at risk. Or perhaps he'd talk about his experiences with Voldemort that he's been keeping to himself. This could potentially change the whole dynamic between the characters in the fanfic, especially if Umbridge uses this information to her advantage.
There are some fanfics out there where Harry is given Veritaserum. Some of them focus on the comical aspect of it. For example, Harry might accidentally drink Veritaserum at a party and start blurting out funny things about his classmates. Others might take a more serious turn and use it as a plot device to uncover a mystery or a conspiracy within the wizarding world.
Harry might initially be shocked and try to resist. But since Veritaserum is powerful, he would soon start answering truthfully. He could look angry towards Snape for using such a potion on him without his consent.
He might face danger or threats. People might try to silence him to keep the secrets he knows.