Im trying to to find a story but I cant seem to remember the name of it. Their is this one scene in the story where malfoy comes to antagonize harry and hermione. He insults hermione which cause harry to act. He asks to speak with malfoy. They sit in a compartment with hermione waiting and watching through the window. Harry is calm and relaxing back in a seat while malfoy becomes unnerved.

Harry warns malfoy that hermione is off limits with his disparaging comment. Malfoy writes that off with a sneer. This ends up being a fatal mistake as that results in harry grabbing him by the neck, choking him to get his point across. Hermione yells through the window to not hurt him which makes harry stop. He again says Hermione is off limits and that the only reason he didn't do anything else to him is because of Hermione. Malfoy asks about Weasley and harry says hes fair game.

If you can find this fic I'd be grateful...