First of all, tell me a little about your series and introduce us to the sequel(s).
The Ancient’s Blood series is a science fantasy chronicling the events leading up to and during the Retallian Civil War. It is currently planned as a trilogy, but that may change as I draft book 3 and see how many words it is likely to have.
The second book in the trilogy, The Frozen King, is coming out this October, but it was actually written first! It was through the process of revising The Frozen King that I realized I had started the story in the wrong place, needed to go back, and show what had happened to actually bring the characters to the start of The Frozen King.
The Frozen King starts off with a mystery, deepens the conflict that started in book 1, and reveals many secrets that were hinted at in The Awakening Fire.

You can get a copy of the debut here.

How difficult is it to add new characters in a sequel into already established relationships? 
So, none of the new characters in The Frozen King are new to me. I started off writing them. It was far more difficult for me to extrapolate backwards to figure out who my base characters had been at the start of The Awakening Fire.

Is it difficult to continue with worldbuilding for a world you have already built in book 1?  Do you find it easier to switch locations for the sequel and start again with worldbuilding? 
The plot for the Ancient’s Blood series came to me very much as one whole piece. Long before I started drafting The Frozen King or The Awakening Fire, I knew exactly how the series would end, and all of the places it would take the reader before it got there. I remember reading an article somewhere online that recommended SFF writers make themselves a worldbuilding bible. There was a downloadable worksheet; I printed it from our family desktop, answered every question; and I built my world. That worksheet turned out to be a monster, by the way. Like 20 pages. I’m shocked my parents didn’t freak out at me. The series has been in my mind for so long that I don’t even look at the worksheet anymore. I know all the answers by heart.

You always define your book as one whose genre is weird. Could you tell me more about it?
My books exist in a universe where humanity was seeded across many galaxies by an alien race known as the Ancients. The Ancients had advanced technology when humanity was in the bronze age. Every bit of magic you find in my world is just a piece of technology that the characters don’t understand yet. If I thought people would understand that kind of a world, I would have every book I publish categorized as science fiction. But it’s very hard for people when they read a first chapter that takes place in a medieval setting where certain people’s eyes glow, to believe that what they're seeing isn’t magic. Hopefully, The Frozen King will do a good job of revealing more secrets and opening characters’ eyes to the reality of the world around them.
Growing up I played a lot of Final Fantasy, a video game series that blends magic and technology, and I like to think I took a lot of inspiration from those stories.

Have you ever been stymied by a worldbuilding or plot detail from book 1 that is very inconvenient to deal with or write your way around in subsequent books? 
Yes! I’ve never had the little details set in stone. Since finalizing The Awakening Fire I keep having to look back and check what color certain people’s eyes are. And it has actually caused a problem. I have a scene in book 2 that I just revised a few weeks ago where the color that I chose for Gannon’s eyes in book 1, is causing an argument with a character in book 2. I used to be able to just change these things to suit what I needed. Not anymore. It’s a strange feeling.

Would you say your craft has improved since you published your first book?
My craft has definitely improved since book 1! I am in the process of editing The Frozen King right now, and there are so many little things I keep catching that I only know are issues because I’ve worked with a professional editor before. There is a catalog of knowledge in the back of my mind that I can only assume will continue to grow with time.

How do you market your books?
I haven’t tried many avenues of marketing yet. I tried a book tour when The Awakening Fire first released that was a horrible, horrible failure. Not doing that again. I ran an ad with Bargain Booksy that was also a failure, but I’m going to try another one. The only marketing I have tried and stuck with is sending out free review copies of my book to reviewers with a platform. Is it working? Yes. But it’s a very slow process. 
I don’t foresee myself using Amazon or Facebook ads anytime soon. I’ve considered hiring a billboard in Portland (supposedly the city in the US with the highest percentage of readers), and I’ve considered signing up for those little postcard mailers that go directly to people’s mailboxes.
I guess the point is that I don’t have a method yet, and I’d rather save my money for developing The Frozen King than spending it on marketing for The Awakening Fire.