Yay for more questions!
1. How long have you known that you were going to end the story the way you have?
I feel so bad with these questions because I honestly don't remember! I always knew that James was going to be a Quidditch player with Problems, and this seems like the logical solution to that. I think my original draft had him putting more emphasis on seeing his career as coming between him and Carlotta (given she was worried about being a burden and holding him back) but other things have changed since then so that part never made it into the fic proper. So this has been the plan for as long as I can remember, in which case the answer to your question is probably "for almost as long as this story's existed".
2. When you first got the idea for Rails, did you know the whole overarching plot, or did that take a long time to develop?
Again, it's difficult to say. The initial plot idea was the James/Carlotta storyline. I think I always knew that if I was to write a James II fic, it would be about a James crippled by the pressures of being Harry's son, so the minute I decided to make him a Quidditch player, the breakdown idea would have been there straight away. Or perhaps I decided to make him a Quidditch player because I wanted to put him through his breakdown? I really don't know. (These questions will be a lot easier to answer when we get to Derailed because I'm still planning it, so hopefully I'll remember how things unfold in my mind!)
As for Lily, I always knew I wanted to throw a character like her into a fic and tackle the issues that come with that, so the minute I started working on a Next Gen, I knew picking her for that plot would be doubly interesting, with her being Harry's daughter.
3. How do you come up with names for your OCs?
Fun fact: Carlotta was originally called Evangeline. That was before I decided to make her part-Spanish, I think (and THAT was only because I wanted her mum to be Spanish, for reasons which will hopefully become apparent in Derailed). Then she became Carlotta, which is a name I always loved when I was younger and read Enid Blyton's St Clare's boarding school fics. Her mum is now called Evangelina, because I liked the name too much to shelve it completely.
To be honest, a lot of the time I just pick names I like, so long as they fit the character. I mean, there are some names which won't suit a pureblood witch or wizard, and the names which are more suitable for them would sound ridiculous for a Muggle. I remember struggling a lot with Cato's name. I wanted something to match the Bagman pattern - Ludo, Otto, both four-letter names. After that, Cleo was easy. Sometimes it can be fun to name a character, other times it's a nightmare.
4. If you were to write another next generation story, not focusing on James or Carlotta, would you set it in the universe you've created in Rails?
I think I'd have to; it's my head-canon now. I get confused when I read other people's fics and Lily's at Hogwarts. That would be the difficult thing, including Lily as she is and managing to write it in such a way that it wouldn't confuse non-Rails readers. But I don't think I could write about the Next Gen characters if they weren't my characters.
5. Rails is such a long fic - have there ever been any moments when you just wanted to give up? And if so, what advice would you give to people who feel like giving up on stories?
I was fine with writing Rails until about a year ago. I did Camp NaNo and got myself to the World Cup, and about ten chapters away from the end. I then had exams so stopped writing completely, and then I had a busy summer, and then come September I couldn't get back into the fic. Especially as there was so much Quidditch to write. There were times when I wondered if I'd ever finish it! But I got my head down the other month and just ploughed through it, and it was the best feeling in the world to finally finish. I guess if I were to give advice to someone else in that position, I'd say to not force anything, because that can just make things worse. Remember why you're writing the fic, and what you want to achieve from it, and in the end something will hopefully come.
6. Was it difficult to make the switch from writing Gideon in your Marauders era fic to writing James in the next generation?
I started writing Rails just after I started posting Frozen, so for a year and a half I was writing them both at the same time (never juggle WIPs. It's terrible). Frozen actually had three narrators in all - Gideon, another known character, and a few pronoun-only, present tense sections (for MYSTERY). It was a challenge in itself to juggle those, because the two characters were quite different, and the pronoun-only bit got interesting once there were more than two characters involved and there was lots of "she" and "he" to keep track of.
James is actually very similar to Gideon in a lot of ways, especially now James is more mature, so going back to James after writing a bit of Frozen wasn't too hard, especially if I'd been writing Gideon. It was made easier by the fact the two fics are set in totally different times so it was easier to separate them in my head. I think the biggest difficulty was actually the switch from third person in Frozen to first person in Rails. Before Rails, I'd never done first person for anything longer than a one-shot, but I thought Rails needed to be told from inside James' head. Now, I think it would feel odd to go back to writing third person. But equally, first person wouldn't have worked for Frozen. It's odd, that something like that can make such a difference in a fic.
7. What's the main lesson you've learnt from writing fanfiction?
Planning and pacing are vital. In an ideal world, I wouldn't be posting as I write - that was my plan for Frozen, and then also for Rails, to hold them back until they were complete. Instead, I gave in both times after about eight chapters. But I'm fuelled by the feedback from readers, and without that I had no real go-forward, which is why I began posting. I know I'm not going to be able to adopt that approach with Derailed either, because aside from anything else I'll leave you guys hanging for years on end if I did that.
8. This is kind of similar - which area of your writing has improved the most since you started writing fanfiction?
The general narrative, and description within that, I'd say. I think I've always been better at writing dialogue, and in the early days I would pretty much neglect the narrative. Which is very naughty.
9. If you could create your own Quidditch team, what would it be called and what would the mascot be?
...you clearly asked me this because I bailed on the mascots for the World Cup final, didn't you? Um. I'm trying to think of a cool magical creature that could be the mascot. You can't get much cooler than a dragon, can you? As for a name, I really have no clue. That kind of thing is where I completely fall down. I'd just call it after the dragon, probably. Really original, I know.
Thanks for the questions!