Merlin could use his magic to show Harry visions of a better future. By giving him hope, Harry might change his mind. For example, Merlin could show Harry how his actions in the future would lead to great good.
One possible reason could be the extreme pressure he faces. Merlin has to constantly hide his magic in a world where it's feared and persecuted. This secrecy and the fear of being discovered might have built up to a point where he feels there's no way out. Also, his loyalty to Arthur might play a part. If he feels he has failed Arthur in some way, like not being able to protect him fully from threats, it could lead to such despair.
Arthur would likely be shocked and feel guilty. He might think that he has failed Merlin in some way, not realizing the full extent of Merlin's inner turmoil. He would probably become more protective and try to find out what made Merlin feel this way.
The way the fanfiction portrays his relationships can also show despair. If his friends try to reach out but he shuts them off, it's like he's in a deep hole of despair where he doesn't believe anyone can help. And his actions, such as isolating himself in a dark place, could be symbolic of his state of depression.
In this fanfiction, it could be that Paul is under the influence of some evil force or has been manipulated. This makes him do things that go against his true nature. As a result, he feels so guilty and ashamed that he wants to end his life. His Pokemon might be his only hope. For example, his starter Pokemon could have a special bond with him and use that bond to reach out to his heart and prevent him from going through with the suicide attempt.
One possible reason could be the overwhelming burden of his destiny. Harry has faced so many challenges and losses throughout his life. The death of his parents, the constant threat of Voldemort, and the weight of saving the wizarding world might have made him feel so tired and hopeless that he contemplates taking his own life.
Harry might be shocked and full of regret. He had finally come to understand Snape's true nature in the original story. In the fanfiction, if Snape tries to kill himself, Harry could feel that he had not done enough to reach out to Snape or show him some form of forgiveness or acceptance, and he would likely be deeply troubled by it.
In such a fanfiction, one possible reason could be his feeling of extreme isolation. After his estrangement from his family, he might have felt completely alone in the wizarding world. He was always so focused on rules and order, and when things didn't go as he planned, especially in his career and family relationships, it could have pushed him to this dark place.
One possible reason could be extreme loneliness. In the Merlin universe, if Harry felt he didn't belong or was constantly ostracized, it might lead him to such a dark place. Another reason could be a sense of powerlessness. Maybe he was faced with a seemingly unbeatable foe and thought death was the only escape.
Well, in most of the established 'Harry Potter' lore, Ginny is in love with Harry, so a 'ginny tries to kill harry fanfiction' is a very out - of - the - box concept. It could be a dark exploration of an alternate universe where Ginny has been corrupted or influenced by some dark magic or external force that makes her turn against Harry. Maybe the writer wants to explore the extreme consequences of a character going completely off - their - normal - path.