Characters In Multiple Publications?

No I don't think so. If these are separate stories, but involving some of the same characters, I see no reason why a publisher would stay away from a later novel.

I like the idea of carrying characters through to different works. I'm sure there are tons of examples, but a good one is of Huck Finn originating in the first Tom Sawyer book, then getting his own book later.

If your short stories find readers, I'd think it'd help you with selling your novel.

I am just wondering how you could be in violation of copyright over your own characters? Or perhaps I am missing something ...

If you are able to sell your chapters as stories, it will only help you. Several authors sell stories that later appear as chapters in their books. And you are talking about not even using those stories in your novel. Either way there is no problem.

Nah, they're your characters. Several authors reuse characters or fictional locations from earlier novels - just look at Stephen King's Castle Rock novels. Even in novels that aren't set there, he often references his own fictional characters or events that have happened in other novels.

I can think of many novels with characters that first appeared in short stories. And many novels started out as short stories or novellas that were added to or expanded later (Anne McCaffrey's Dragonflight is one famous example).

And I know writers who have published short stories with the same characters in them in different magazines too. For example, I have one friend who has published a ton of short stories and one novel, and 90% of them (probably) are in the same fantasy world. Some of the characters appear in more than one publication too.

Most short fiction markets only hold onto the rights, even to that particular story, for a set time period anyway. Giving a publication indefinite rights to your short story is problematic, actually, as you may want to publish something you've written earlier in an anthology, another magazine, as part of a novel, or even in your own story collection someday.

Read your contracts carefully if you sell a story somewhere, but I don't think it's usually an issue.

You have every right to do this, and doing so will only help novel sales, so publishers are all for it. The novel can also make your name more recognizable, so magazine editors love it, as well.

The problem is simply selling them. Nothing is tougher than selling a short story to a good magazine, except maybe selling poetry to a good magazine.