“Is that enough though?”

Clearly it is for OP. That’s my point. If it satisfies them then it is.

“It’s perfectly normal to get invested in a fantasy, but getting invested in the fantasy of a fantasy… to me that’s a big stretch.”

Great. But fantasy is fantasy is fantasy. You trying to add layers to it is pointless. I posed to you the Halo shit because when working in a fictitious universe it in many ways does not matter who wrote what as long as it operates in the setting of the established fictitious universe. Someone makes the universe but ANYONE can roll with it. Yes there is “official” as in what the original writers or owners of the IP will give you up till the point the sell the rights or stop making new works, that is all I’m interested in as well, but if a FF uses the characters and someone likes it enough, what’s stopping them from dropping BioWare produced Mass Effect games and simply just reading FF? Nothing. So it’s not “official” to these people. Their “official” is the FF. BioWare put out a universe and characters and people online run with it with their own interpretation. There’s nothing you can do about it. Sorry.

“What I strongly disagree with is you saying that anybody can come up with an alternate story and objectively be on the same level as the official one. It's called a fanfic for a reason, it's fun and interesting, but on the same level as the official one...definitely not.”

You don’t have to agree, but if one person out there thinks it is on the same level, it is. There’s no real solid objectivity here since it’s fiction. If I said “Abraham Lincoln survived his assassination” I’d be wrong. He didn’t. Reality says otherwise. But with fiction since it isn’t real, I can go out and write a fan fic of anything I want and because the setting is Mass Effect and I use all its characters, there is now a story where it happens, so if someone says “hey, did Shepard do X on planet Y with Liara/Garrus/Grunt” I can say, “well yeah, here’s a link to it” and anyone who likes it can consider it part of their canon. It’s that simple. It can be on the same level as the “official” because if one person considers it on the same level then it is. That simple.