Safest bet, certainly. Lorena would have to have a new origin. I like the cleaner, more Atlantian origin for Dolphin, as you do, so it might be ironic if I end up giving Lorena an expirmented-upon origin (I'm cutting down on entire-city destructions). Cerdian is easy enough (and you do not know how it irritates me that DC couldn't keep the child's sex straight), I just have to have Garth and Dolphin hook up at some time. Since I have no particular ship that I like for either of them, that's not really an issue, whether short or long term. But their entire romance would have to be redone.
But Koryak is the biggest issue. How much could I change his origin while not just making him a different character with same name? Firstly, of course, he won't have the same tie to Orm, because I'm going with a shared mother (Atlanna) rather than shared father (Atlan) for Orm and Arthur. Secondly, I have to figure out how old I want Arthur and at what point in the narrative it makes sense for him to have a grown son. If I make Koryak his son - that's the part I think people would be most up in arms about me changing. But
I have issues with Arthur on the throne already. This ties in with my issues with Atlantis being depicted as such a xenophobic and racist society. You can see it further highlighted on the
Aquaman tv tropes under "Humans are Morons" and "Refusal of the Call" and "Fantastic Racism" sections. Not necessarily how I view every circumstance, but certainly Atlantis has become a much worse society then when originally introduced (as have other fictional DC civilizations as comic books changed). An outsider (because Arthur is never raised in that culture, never one of them in that way, even when full-blood) coming in to rule and "fix" the kingdom has undertones I don't like. And then if he, as "bastard half-breed" (assuming the marriage wouldn't be recognized by Atlantean law), can be king, then his son, a bastard quarter-breed, can also inherit the throne if recognized. And he's another one not raised in the society, which just exacerbates the issue.
And there's Arthur's current abandonment issues. They make sense, and I'm good with that as storyline. But it needs to be storyline that
ends and not just a persistent character trait that hangs around forever to me. I'd rather he find some peace on it. But if he finds out he effectively abandoned his own son (well, he never knew, but you know it's got to feel that way), so I think that's the kind of drama that could go well or terribly.
Tula, I just have to decide on a version - I do kinda want her and Garth dating as teens - they were cute.
Garth, do I still want him as Aquaman's protege? Because he was very much a son to Arthur in those early stories, IMO. And if he is, I'd think Arthur's abandonment issues might kick up then, when he decided to keep the boy, rather than just later, when he was facing impending parenthood. He'd already be a parent, although it'd feel quite different, since it might happen more gradually, and with a much older child. But you don't want to deal with that Arthur-abandonment-issue-as-parent thing
three times because it's just repetitive.
Then, of course, we get into more throne-inheritance issues and bio v. adopted (legally?) children and so forth. Presuming, of course, Arthur, rather than Mera, holds the throne. If either of them do.
And, oh, timing. If I have Arthur come to Atlantis in early 20s (shortly after father's death), should he meet Garth and Mera then? If so, then is Garth still 15ish when Aquababy born? And Koryak would then be 6 or 7 years older than Aquababy? Could make Arthur older (or not meet Garth for a few years after coming to Atlantis), though. So many choices.
I have a fondness for older versions where Arthur is not the king, but there's really not much mythology to work with there, and it's frankly against audience expectations now.
EDIT: Does anyone else tend to forget Arthur Joseph Curry exists?