Danny had acquired a few weird habits over the months he was ghost hunting. One of them happened to be very frowned upon, but he had a reason. Because, well, he'd see these people standing around a casket. Sometimes he'd feel so responsible, because if he'd just been there just one minute sooner, this person wouldn't be six feet underground. So, Danny would find himself floating invisibly over the service, and he'd be there to guide that one lonely ghost away from the grave and to the portal.
One of the ghosts was a girl in his math class. That funeral was particularly hard for him, because this was a girl he'd spoken with, had actually known. He'd wound up telling her about him being Danny Phantom, she would have found out in the ghost zone eventually. She was pretty shocked, to say the least.
Another one of the ghosts had been a little girl. She'd said she was his biggest fan, and had been awed to get to meet him. Danny didn't think she fully understood she'd died.
Danny didn't have the heart to tell her, in the end.
The funeral Danny was attending was different from the others. His family was there (he found himself wondering why the heck he hadn't been told about it), as well as Sam and Tucker, even Vlad, and some people from his classes. Dash, of all people, looked particularly upset, maybe guilty. Danny wondered what he'd done, if his bullying had gone too far. Had somebody killed themselves?
He was scared to look inside the casket.
Jazz had broken down halfway through the funeral, and had to leave. Danny wanted to go comfort her. He had a sneaking suspicion that he needed to look in the casket. He was scared to look inside the casket. It was an open casket funeral. All he had to do was float over all the heads, check out who had died, and take them to the portal. Simple. Easy.
Danny wondered how they'd died.
(He found out later that they'd fallen to their death from an impossible height.)
He'd wondered if he would have been able to save them.
(He probably could have, if he'd tried harder.)
He'd wondered if he'd see himself inside that casket.
(He did.)