In Another World, timeline C is exactly the same as timeline B, except it includes Kid's travel which does nothing. Wazuki still kills Serge. and FATE still kills Miguel. Home World Serge then dimensionally travels there, called by Kid.
In Home World, 1010-C is different. Wazuki fails to kill Serge, though still becomes Lynx. Kid goes back to Another World.
That does seem to be how it had to happen, and I think I've got the Miguel thing straight in my head now. The bolded part above is the only other thing I'm held up on. If we assume this, it means Kid basically traveled from Another World to Home World, and then back again. I mean, Kid is Schala for all intents and purposes, but this just..... feels wrong to me. I find this explanation much more appealing (until a hole is shot in it, as it invariably will be
).
I don't think Serge's probability of life or death is what causes the dimensional split. I do think that Serge had a 50/50 chance of life or death, just as Belthasar said, but he said an event happened that caused it. I believe it was that event that split the dimensions, and that event was no more than Kid's time travel back to 1010.
I've read people debating and thinking about why this event split the dimensions instead of just creating a new timeline, and sending Another World to the DBT. It didn't seem like an answer could be reached, but I think the answer is very simple. Kid's time travel worked exactly like every other time travel in Trigger (
maybe with the Marle Paradox exception), but we're just asking the wrong question.
Instead of asking why Kid's time travel was unlike those in Trigger, maybe we should be asking why Trigger's time travel was unlike Kid's. Why didn't we see a dimensional split everytime Crono and Co. traveled? Maybe the answer is that there was a dimensional split, but since no one had the power to traverse them, everyone involved remained ignorant of it. "There are as many worlds as there are potentialities."
I guess what I'm theorizing is simply this - every time travel splits a dimension in two: One dimension where the travel occured, and one where it didn't. Simple as that. The dimension in which the time travel does not occur might be sent to the DBT, but it remains a functional dimension nonetheless. The split occurs at the travelers destination point - in Cross' case, Opassa Beach at 1010 AD. This becomes an entrance to the DBT, since that is where Another World has been sent, and could be why Serge could access the Time Devourer there. Also, Serge can traverse the two dimensions because he is an Arbiter of the Frozen Flame - something capable of viewing and acting in both dimensions.
So, in Cross, in 1010 AD, Kid appears in Home World to save Serge because she time traveled. In Another World, she doesn't appear, just as she didn't appear originally. Another World is nothing more than the original time line, before Kid did a darn thing.
A couple evidences of this - one is that no one in Another World seems to remember a girl nobody knew appearing on the beach the day Serge died. Lynx never says anything about killing her once already, for instance. If that had happened, you'd think he'd have something to say about it. Nobody in Arni Village remembers her, either.
Secondly, Kid is exactly as she should be in Another World, having seemingly no recollection of meeting Serge prior to Cape Howl. She could be acting, but I don't buy it. I'm sure she did call to him from Another World (on Belthasar's orders) but still didn't show any signs of recognition when she finally did meet him.
Lastly, my real basis for this theory. Cross isn't the only dimensional split we hear about in the series. There is another event that is known to split the dimensions in two - Lavos' landing. Dinopolis existed in a dimension in which Lavos never fell, not in which Lavos fell and had no effect. Therefore, Lavos' landing on Earth split the dimensions in two, and the dimension in which Crono & Co. existed was the resulting dimension - the Reptite dimension was sent to the DBT. However, the fact that Dinopolis still existed to be pulled in proves that, even though that dimension may have been in the DBT, it still functioned.
It's also been debated that Lavos' landing was a form of time travel, since he was so technologically advanced. I would support that theory, because his arrival split the dimensions, just as Kid's seemed to.