I think so. Though I feel I should clarify that by Original I meant an original world setting, not The Originals the TV show.
Out of the ones you mentioned Age Gap/Size Dif/Mpreg/Mates are totally my favorite combo! I would love to do something with all of those mixed in together. As for fandom... doing a kinda HP/MCU or HP/Teen Wolf fusion is always fun (and yes, FB counts). Would you liked to discuss further in email or custom?