Hello there! Thank you for your questions:3
1. Simply put, I chose Lucy as the main character because I've got a bit of a soft spot for Percy. Of all the characters in Harry Potter, I feel like I can identify with Hermione, Colin and Percy the most, being a short know-it-all elitist bighead with a soft spot for photography and irritating people as I am. When I started writing Next-Gen, I got thinking about what Percy would be like as a husband to Audrey, and as a father to Molly and Lucy (as they were named in JKR's family tree). For some reason, I imagined that poor Percy, who'd probably still be fighting the cause of cauldron bottom regulation in government, would end up with a pair of mildly rebellious daughters. And that's where my Lucy came from! If I had more time and energy, I would have written more about that branch of the Weasley family, but sadly there's only so many hours in the day.
2. I can't really name anything specific beyond my absurd sense of humour! I was raised on a diet of Douglas Adams, Terry Pratchett and the Monty Python films, and I feel like a lot of my sense of humour has come out of that. I also have to credit TV series like Black Books and Green Wing, and comedians like Bill Bailey - I like to laugh at the surreal, and I think a bit of that's been injected into my writing along the way. Besides that, I tend to draw on real life as often as possible - sometimes me and my friends do just have these bizarro injokes that I end up mashing into stories. For example, our generic name for posh hipster boys is 'a Tarquin', ergo...Tarquin.
One of the most important things to do in writing generally, I think, is to observe as much as possible. I read a quote earlier about how writers kind of exist on the periphery of life, always observing, not really part of the action, and I think that's totally true. When you take a step back and think about life, it is totally weird and very random. Things tend to happen very slowly and, uh, very uncontrollably. While I don't exactly advocate a plot twist per chapter, I think it's important to remember that uncontrollability when you write. I'm just an average human being; I'm a bewildered, baffled sack of bones blundering blindly from thing to thing. I do a lot of stupid things, and I don't understand most things. Life is just a lot of things. The same goes for my characters.
So, uh, not to be a Percy and sound bigheaded or anything, but I think the absurdity and spontaneity in my stories comes from my habit of observing and appreciating the inherent oddness of being a wee human being in a big, messy world. I think it's important to notice things, even if they're little. Notice quirks of behaviour that your friends and family have, for example, and write that into your fic.
But mostly...I'm an art student. I get exposed to a lot of weird things. Surrealism is kind of the background radiation of my life.
3. Ah, sort of! They're not exactly based on individuals. I think I kind of threaded a lot of people I knew and didn't know together and then cut Raven and Tarquin from the resulting cloth. I don't really know anybody I can directly match up to them, whereas I can definitely say that Scorpius is so much like me he's almost an author-insert, Rose is a bit like me too, and I gave some of my own physical attributes to Lucy (simultaneously giving her the sort of confident personality I wish I had, eek!). Whilst characters are certainly inspired by people I know and have met, I don't think I've ever totally based a character on someone I know. I'd find that a bit odd - I'd end up thinking of the character as them, and not a separate person, and that'd complicate the writing process, I think.
Thanks again, and sorry for the enormous reply! I get a bit excited when people ask me things about my writing, heh.