Here's a boy, no older than nineteen, quietly sipping from a mug in an interdimensional bar. There is a rather large rather ponty-eared panther lying next to him, purring softly as the boy scratches its head. Floating in front of his face is a book, which he is absently reading. Given that he didn't walk in from the door, it can be presumed he is probably a tenant who came here from one of the rooms upstairs at some point.
"Cool. Anyway, maybe we should go back to the slideshow of tears? I want to see if we can make Fernando emote or if his facial muscles atrophied."
The slideshow of tears never really stopped. Past Katur holds the door just like present Katur is doing, and they follow their shades back to the great warehouse where they set their portals up.
Once the portal to Sadde's Earth settles, Kaede casts the invisibility spell on him and he grows wings. He's visible anyway, but that might be just because the spell anteroactively retains its exceptions for the triplets and Katur.
Eriol does not visibly react when Sadde strips naked which is perhaps evidence that the invisibility spell is working. Or perhaps Eriol merely doesn't care.
"Undress? I do believe that is an ability we all share. Grow wings? In a roundabout way."
So apparently he can see Sadde in spite of invisibility, then.
"I'm surprised to hear you say you hate it," he comments, watching his alt fail at getting airborne.
"I meant that he is stuck with five people and it would be fun to have four of him in our lovepile."
"I have suspicions about how his... ultra-pentagamy... will interact with polyamory, but I do not trust them too far, being unfamiliar with the magic."
"If you don't count the time I spent dead I'm almost four hundred years old and I spent most of that time refining and developing magic, and my magic system is rather good at information-gathering and divination."
"My suspicions are that Sadde will not ever want to, themself, be with anyone other than the five of you, but that they will not care if you are with anyone else. I also expect they might join in any... activities... where you are involved regardless of who else is but won't have any enthusiasm for others."
"If I understand their magic correctly I do not believe they see themself as unfortunate. It will be... confusing, I expect... to see alts of their mates, however."
"You... should probably not open your eyes until the turning process is over and everyone else you want to mate to is around. Or, at least, everyone who hasn't yet mated on you."
"If you do turn, you will become as hyper-whatevergamous as Sadde is, though. And, yes, it's probable you'd be able to mate on yet more alts, and you'll meet more. You'll meet my Sadde someday."
"Not as much or well or clearly as I once could, and there are limitations to how much I can see of the multiverse, but yes."
"Could you show us the future? Can you use it to..." Katur waves, "get messages from your future self with the answers you needed in the present?"
"I cannot really show the future, and when I say I can see it it's not anything as high-definition as this. I can get answers to certain questions, almost always vague, and I can know various things that will happen without actually being able to watch them happening. But getting answers from the future was how I figured out that the near-apocalypse was the best I was gonna be able to do."