Initially, when
A Burning Passion was released as an event, Lightning and Serah were not yet available as PCs (Chapters 8 and 9 hadn't been written yet). The three cutscenes in the Snow event contained characters from Chapters 1 and 2, and the snowy environment implied that the event took place sometime during or shortly after Chapter 4. The last of these three cutscenes, "The Will to Protect All of Us" contained the following dialogue:
Snow: I can't allow my home to be destroyed. I've got someone there I care about, you know? I'm not going to let anyone get hurt.
Cloud: Pretty sure of yourself, huh?
Cecil: Do you really think you can do it all on your own?
Snow: It's not gonna be easy, but I'm sure it'll all work out. It always does. Besides, I'm not alone. I've got you guys, right?
Zidane: That's the spirit! I think we're gonna get along just fine. ...So, is this someone you're trying to protect really that cute?
Snow: You bet she is. I could go on about her all day. ...So I better not see you try to make a move on her.
Hope: Don't worry. Her sister would kill you before Snow ever got to you.
Zidane: Y-you don't say. Sounds like Snow has it rough back home.
When they turned the event into a Lost Chapter, they added two new cutscenes before "The Will to Protect All of Us" ......
one of which includes both Lightning and Serah. The dialogue from "The Will to Protect All of Us" has not changed, it has just been made nonsensical, because everyone was just being chummy with the people they're now hearing about for the first time. And you
have to watch the cutscenes in that order. This lack of attention from the storytellers is ALL over the place in OO. It's what made me want to do that google doc, but the closer I look at the story the more blatant inconsistencies and laziness I find. It makes me wonder why they bothered to include a story at all.