I'd be interested in Prince/Princess x Knight/Mage/Whatever, Princess x Thief, Best Friend X Best Friend, Jock/Popular X Nerd/Emo/Outsider, Rock Band or Mafia/Organised crime for possible originals (My best genre is medieval fantasy but I'm also pretty decent at other settings). Fandoms wise I'd be interested in your Avatar the Last Airbender OC x OC idea. Possibly Avengers but I don't know I'm not to good at canon x OC and also possibly Guardians of the Galaxy just I'm not sure how well I could roleplay either character.
Writing Sample related: I'm assuming you mean a roleplay sample, right? :P Cause I mean I could post a short story I wrote or a snippet from a novel I'm working on but that doesn't really sum up my roleplaying ability rather just my general writing skills