Huh. You'd think a Touhou fanfic thread would be pretty active, not silently die after the first post. Well, here's my attempt at reviving it.
I recommend Sendai Hakurei no Miko Mode by SKOOLATOON for those who want a fanfic that has the fabled fan-made OC known only as the Sendai Hakurei no Miko / Previous Hakurei Miko (commonly held to be Reimu's mom or older sister; the former is the case in the aforementioned fanfic). As far as I've seen, she's not overpowered, but is definitely hella strong and while she keeps reaping a constant streak of victories, they're almost never easy... and sometimes the youkai she's facing was holding back all along, and Sendai herself would note that she probably would've lost outright had the youkai in question gone all-out from the beginning (prime example: the battle with Remilia Scarlet).
Fiat iustitia, et pereat mundus.
Or something like that. If there's a decent Touhou fic you've seen somewhere and want to share, drop a link here along with your opinion of it.
Wolfsbane706, at your service.