I thought I remembered at one of the events earlier this year that they were an estranged Ultramarines successor, though I could be mistaken.
They were described as such repeatedly at the Weekender; Aaron gave that reason for his being on the Ultramarines panel.
Yep. They're a lesson/reminder of the scale of the setting. 60% of Space Marine Chapters are from Ultramarines gene-stock. That doesn't mean 60% of Chapters are just Ultramarines-lite, or even similar to the Ultramarines.
I've never liked it when Chapters are shaped purely by their genetic code, or that being their defining trait. Homeworld, culture, and actual experience over the course of centuries/millennia have a far, far greater role.
EDIT: See also - the Celestial Lions, Executioners, and Black Templars. They're not just Imperial Fists.
I get the feeling you're the only writer I've seen who does that. Because all I've seen of Ultramarines successors, barring the Mortifactors or Iron Snakes are "Ultramarines, but a different colour". Same with the Imperial Fists (barring the three you've mentioned) and Dark Angels
Good to know you've tried to change that with your writing.
Haley's Novamarines and his BA successors to a degree, pretty much anyone who writes Flesh Tearers stuff, Kearney's Dark Hunters was pretty apart from WS with a different flavor. Unfortunately DA successors on the rare occasion they do appear get pigeon-holed into being super similar to DA, but I think the problem is a lot less that successors are the same as their parent chapters, rather that we really just don't see a lot of Successor fiction. It's good to see something like Spear of the Emperor coming out to kind of provide alternatives to the Big Few, as it were.
There's probably some kind of sales/marketing justification for the majority of works being about First Founding Chapters, but whatever.
That's a very good point. Visibility, not a setting-wide statement.
And there's safety in the lore, too. Plenty of Successor Chapters are very similar to their parent Chapters, like the Genesis Chapter or plenty of the Blood Angels and Dark Angels' Successors, f'rex. "My" Chapter, the Angels Numinous, are more or less the Blood Angels with their serial numbers filed off, and slightly meaner. So I do it as much as anyone, and it's totally valid.
But yeah, it's definitely a marketing deal, at times. And not necessarily in a money/mercenary way, but in the sense that a lot of the time, the books promote the lore people like and are familiar with, because they're the audience. That's what they expect and want, and are familiar with from years of the lore.
Anyway, I'm going back to being too scared to read any opinions of the novel for another, say, 5-6 weeks. The book release ritual demands nothing less.