You know who you just clicked? Star Sapphire.
You know who she claims to be? An innocent fairy.
You know who she ACTUALLY is? A deranged psychopath!
Here's the evidence:
1. Look at how happy she is with herself, knowing that several bombs are about to blow up in Reimu's face. She's launched bombs and threw knives at her in the past, too.
2. This was not a one-off occurence, as the other fairies are clearly growing weary of her insanity.
3. Look at her, ecstatic over the idea that she and her friends were about to be cut down with a sword by Youmu.
4. First example of her enjoying watching other people fight each other.
5. A being supposedly meant to represent and control lifeforce, fascinated by the very opposite of life? Hmm...
6. Second example of her enjoying watching other people fight each other.
Or perhaps she's just enamored by the idea of Clownpiece commiting arson and the Hakurei Shrine burning down?
7. In the last panel, you can see she's guiding Luna to hit Cirno with a stick. Cirno knows this, as evidenced by the little drop thing on her bow.
8. She takes pleasure in Sunny getting hurt...
9. ...and she's not afraid of dishing it out herself, especially when Cirno's involved, it seems. The rest of the crew questions her behaviour.
10. Nibbling on a fellow fairy, while talking about hunting and eating her kind.
So yeah, as far as I'm concerned, Star's fantastic. If not for Cirno, she'd be my favourite fairy, hands down.
Go read Touhou Sangetsusei if you want to see more of her shenanigans. If you took out maybe two chapters off Oriental Sacred Place, it'd have pretty much the most satifsying pacing and plot progression of any slice of life manga/anime I've seen.