Maybe Harry is crying because he misses his parents. He often feels the pain of their absence deeply, and in this fanfic, when Sirius sees him, that could be the cause.
Sirius would probably be shocked at first. Then, he'd likely feel a deep sense of sadness and guilt. He might think that he should have been there more to protect Harry from getting those scars.
One possible plot could be that Sirius, upon seeing Harry's scars, is filled with rage and a renewed determination to fight Voldemort. He might see the scars as a symbol of all the pain Harry has endured and vow to protect him even more fiercely.
One possible fanfic could be titled 'The Grief of Harry: When Sirius Fell'. In this fanfic, it might show Harry's immediate reaction of shock and disbelief. He might stand frozen as he witnesses Sirius's death, then slowly sink to his knees, tears streaming down his face as he screams in anguish. His world would shatter, and he'd feel a loneliness like never before.
Often, the fanfic will show Harry crying while remembering all the good times with Sirius. It might be a flashback of them joking around or Sirius giving Harry some important advice. These memories make his crying even more heart - wrenching as he realizes he'll never have those moments again.
One possible reason could be that Harry is feeling extremely overwhelmed with the challenges he faces in the wizarding world. Sirius is like a father figure to him, so in front of Sirius, he can let out all the pent - up emotions. Maybe he's had a tough encounter with Voldemort or his Death Eaters, and the fear and stress finally break him when he's with Sirius.
Yes, there are some fanfictions with this concept. In the Harry Potter fandom, writers often explore alternative family relationships through fanfics. This particular idea of Sirius being Harry's dad can lead to some interesting storylines, like re - imagining how Harry's upbringing would have been different if Sirius had been his father from the start.
Cedric might immediately go to find someone who is closer to Harry, like Hermione or Ron. He realizes that they might be better at dealing with Harry's emotions, so he fetches them to come and comfort Harry. This shows Cedric's understanding of Harry's relationships and his concern for Harry's well - being.
Sirius helps Harry become more confident. By sharing his knowledge and experiences, Harry feels more capable. For example, when Sirius teaches Harry a difficult spell, Harry realizes he can master things he thought were out of his reach.