haha wow you found an olddd post @nannycanes xD that AU has changed a bit since then (and i don't think i ever posted any updates on the concept?) so I'll try to elaborate a bit right now!
the ‘other version’ mentioned in the OP is actually Cascade (which i just updated btw!) and from the start I knew that the two concepts would never be compatible. it's not obvious yet, but some of the later plot points I have written for Cascade 100% wouldn't work if Damas was brought in sooner, and those elements are far too integral to the overall story to scrap them in favour of ‘brothers’ (as much as i love that concept too, and as tempting as it would be to include my fave as soon as possible, i ultimately had to set it aside).
while ‘brothers’ started out as a simple divergence from Cascade, I've since made them two entirely separate AUs (so that ‘AU of an AU’ comment in the OP is no longer accurate). there are still a few similarities that have held over from Cascade (such as the dark Jak element) but the two concepts now have completely different divergence points and setups. this has allowed me to explore some new and interesting plot points in ‘brothers’ that wouldn't be possible in a Cascade divergence, and I think the story is a lot stronger for it!
the divergence point for ‘brothers’ actually occurs pre-TPL; Dax never becomes an ottsel in this AU, and he & Keira reunite and work together to rescue Jak from prison! I'm not yet sure how I'll handle that portion of the concept because the Dadmas arc pictured in the OP is still very much the core of the story & the part I most want to tell, but I might give the rescue arc its own oneshot since there's some pretty fun ideas there too.
Jak starts going dark much sooner than in canon because Erol initially suggests that Daxter was captured too– the lie doesn't last long (because Erol would definitely have made them watch each other being tortured & used that as leverage) but by the time Jak works this out the damage has already been done, leading to him stuck in his dark form like in Cascade.
because the dark Jak transformation happens much faster/sooner, Jak never got to go through the full process of teaching himself to speak & would still struggle with it a lot even if he were able to revert (he always defaults back to mute while in darkmode so this doesn't make a huge difference in a story where he's stuck like that at all times, but still... it's very likely he'll never be truly comfortable speaking in this AU even if he eventually finds a way to revert).
‘Sig finds the Kid and then Kor steals him back later on’ is pretty much what I've already got planned for the plot! there's a lot more to it ofc (including some good family fluff after Dadmas catches up but before the Kid gets recaptured) with the action culminating in the battle at the metalhead nest & the big Reveal. it probably won't follow the exact beats of those early sketches (especially since those still have ottsel Dax in them) but the core ideas are the same!
((....tho fair warning that ‘brothers’ is inherently a bittersweet concept, as smol Jak must be sent back in time to complete the time loop– if he never goes back then his older self can't exist, and other parts of the loop would fall apart too, and you end up with one VERY BIG MESS which is also another fic concept i'm working on but shhhh so yeah, without giving away any details, it should go without saying that the Kid going back in time is inevitable. ;u; ...and once Jak has had the time to really think about it he'd definitely be in favour of sending his younger self back, even if the paradoxes weren't a problem– staying in the present would mean abandoning Daxter's past self to be alone among people who hate him, and Jak would never willingly do that to Dax))
