And you got my prompts! I know, I'm the mod, but please don't let that bug you in any way. It kinda messes with the anonymity part of Summergen but that's all.
I know I'll love any story you write for my prompts. What matters most is that you have a blast writing it. So don't feel you need to stick too closely to my ideas if you find the muse is leading you elsewhere.
In terms of genre I'm very easy to please. I don't do well with comedy because I haven't got much of a sense of humour so I often don't get the joke, but gentle humour or out-and-out crack is okay. Beyond that, I have genre dislikes in slash but none of them apply to Summergen ;)
If you glance over my fic (it's all on AO3) to see what I like you'll find that as a writer I lean toward plotty, angsty stories with a side of dark. I have a 'thing' for character deaths (except John Winchester. Him I tend to resurrect a lot!). But as I reader I enjoy many genres I would never write myself.
I love Sam and Dean (Sam slightly more than his brother), but I do not insist on them being major characters in your story. They don't have to appear at all. I am completely in love with John and would love a fic that includes him, but I won't be disappointed if he doesn't appear. I am not a huge fan of Castiel, but as long as he's written in character I can enjoy him in fic. Really, I'm easy to please.
The only thing I really, seriously dislike is writing in the present tense. Unless there's a good reason to do it, present tense just reads to me like, well, lazy at best and illiterate at worst. It just puts me on edge. I have seen some beautifully written fics in the present tense, but it does make it harder for me to enjoy a story.
Oh, and I absolutely loathe RPF, but I think you'd be hard pushed to twist any of my prompts into that, so we should be safe there.
So take what you want of my prompts and just let yourself run with it. Have fun and I know I'll love the result.