Prompting for something that short is tough. General troupe lists seem good, likes/dislikes, mentioning character traits or actions you'd liked explored is also a good tactic. Ttry not to be specific in a way that requires a lot of set up.
Like "House is an asshole, I'd love to see someone shut him down" seems like it could done in 300 words. But "House is an asshole, I'd love it if you explored how season three could have gone if he'd learned from his mistakes with regards to how he treats his team" seems way too big for 300 words. Though it could be done. Maybe phrasing it differently would work "My favorite season is the third season, anything dealing with the team where House acting like an asshole ends up backfiring" might be better.
Re: Chocolate Box
Like "House is an asshole, I'd love to see someone shut him down" seems like it could done in 300 words. But "House is an asshole, I'd love it if you explored how season three could have gone if he'd learned from his mistakes with regards to how he treats his team" seems way too big for 300 words. Though it could be done. Maybe phrasing it differently would work "My favorite season is the third season, anything dealing with the team where House acting like an asshole ends up backfiring" might be better.