Snape could also deduct points from Harry's house. This would not only disappoint his housemates but also put his house at a disadvantage in the house cup competition. Given Snape's dislike for Harry, he might be quite harsh in this regard.
Well, one possible consequence could be detention. Snape is strict and would likely punish Harry for breaking school rules by smoking. He might make Harry clean the Potions classroom or do some other unpleasant chore.
He's probably furious. Snape has high standards for student behavior, and smoking is definitely not acceptable in Hogwarts. His face might turn red with anger, and his eyes would narrow as he glares at Harry.
She might get detention. Snape is strict, and cutting class is a serious offense in Hogwarts. He could assign her to clean the potions classroom or help with sorting ingredients in the dungeon.
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.
Harry might become more determined to prove Snape wrong. He's a stubborn character, and Snape's yelling could fuel his desire to show that he's not the misbehaving student Snape seems to think he is.
Perhaps in the fanfic, Snape discovers a powerful and dangerous magic that he wants to use for what he believes is the greater good, but Harry sees it as a threat. Harry has always been wary of Snape, and this new discovery could be the tipping point. Also, if Snape were to make a deal with a dark force in order to gain knowledge to defeat Voldemort but Harry misinterprets his intentions, it could lead to Harry killing Snape.
Another theme could be stress relief. Given all the challenges Harry faces in the wizarding world, smoking in the fanfic could be portrayed as a way for him to relieve stress, much like some people in the real world use smoking for that purpose. However, this would be a rather unorthodox take on the character. It could also explore the idea of how his friends react to this new habit, leading to themes of friendship and acceptance or non - acceptance.
Sirius might confiscate whatever Harry was smoking. He would then sit Harry down and have a serious conversation about the importance of making good choices. He could also remind Harry of the dangerous magic substances that might be out there that are far worse than normal cigarettes and that he should stay away from any form of harmful substances.
After saving Harry, Snape may have to deal with a lot of mistrust from some people in Hogwarts who don't understand his motives. However, he might also start to form a closer bond with Harry, which could change the whole dynamic between them. This new relationship could lead to some unexpected alliances and enmities within the wizarding world. And if the Dursleys were to try and retaliate, Snape would have to constantly be on guard to protect Harry from any potential harm they could cause.
On the other hand, not competing might lead him to find alternative paths. He could start his own non - competitive projects or groups, which could have a big impact on the fanfic's community in a different way. For example, he could form a study group for magic that focuses on sharing knowledge rather than competing for grades or status.
Perhaps Snape would force them to work together on a task as punishment. This could be something like cleaning the Potions classroom without magic or helping in the Forbidden Forest. During this time, they might start to understand each other better. Harry could see that Draco isn't just a spoiled brat all the time, and Draco could see that Harry has more depth than he initially thought.