Hermione would likely be a mix of disappointed and worried. Disappointed because Harry is usually responsible, and worried because she cares about him. So she'd probably try to figure out why he got drunk in the first place.
In this fanfiction situation, Hermione's reaction could be quite complex. At first, she may be shocked and angry that Harry has let himself get into such a state. But then, her natural caring side would take over. She'd likely stay by his side, making sure he's okay. She might also start thinking about what has been bothering Harry so much that he resorted to getting drunk, and she could be determined to help him through whatever it is, whether it's problems with school, his past traumas, or his relationships with others.
She probably comforts him right away. Hermione is a very empathetic person. She might give him a big hug and let him cry on her shoulder.
Often, Harry will offer her a handkerchief or a tissue if there is one available. He might also put his arm around her in a comforting gesture. In 'The Common Room Crisis' fanfic, he does just that and then stays with her, listening intently as she pours out her feelings. He is patient and understanding, which is in line with his character in the original books. He tries to make her laugh or at least smile by sharing a joke or a funny memory. This shows his deep friendship and care for Hermione.
Snape would likely be shocked and then enraged. Harry is supposed to be the hero of the wizarding world, and seeing him drunk would be a huge disappointment. He would most likely drag Harry to his office, lecture him about propriety and the expectations placed on him as a wizard, and probably assign some form of punishment like a long detention. But as he observes Harry more closely during this time, he might start to wonder what drove Harry to this and if there are deeper issues that need to be addressed.
Fleur could be a bit hesitant at first, not fully understanding the situation. But once she realizes the gravity of Hermione's state, she becomes determined. She might call for help from other reliable wizards or witches she knows. Fleur would also comfort Hermione, telling her that she's safe now and that they will find the culprits. She may use her Veela charm in a subdued way to soothe Hermione's distress.
Ginny's reaction could also involve a sense of helplessness at first. But then she'd quickly gather herself and use her resources. For instance, she might call on her friends and family for help. She'd be by Harry's side constantly, using her presence to comfort him and also using her knowledge of magic to try and ease his pain.
He may show a rare moment of kindness. Given his own past traumas and experiences, he might empathize with Hermione on some level. He could offer her some words of wisdom or even some form of magical assistance to help her get better.
He might be initially startled. Snape is used to seeing Hermione as a strong - willed and confident student. So seeing her crying could catch him off - guard. But then he might quickly put on his usual cold facade and ask her curtly what's wrong.
She might be initially shocked. After all, Draco is usually seen as this tough Slytherin. But then she could feel sympathy. For instance, she might offer him a handkerchief without saying much at first.
She might be very cautious at first. Hermione is a smart and brave character. She would probably try to gather as much information as she could about the Death Eater without being detected. Maybe she'd use a spell to keep herself hidden while observing the Death Eater's actions.
She might become extremely angry and cut off all ties with Draco immediately. Hermione is a strong - willed character, so she would not tolerate betrayal easily. She could use her magic to create some sort of barrier between them, magically locking him out of her life.