Here with your requested review! I'm sorry it's taken me like 80 years :S
Wow, this is such an intriguing start! I'm so curious about what happened to Freya. All I can piece together is that it injured her a lot and involves a car - so I was thinking car crash? - but she also seems to have lost her hair and I'm not sure why that is. Anyway - you have done REALLY well at setting up a mystery and revealing just enough information to raise questions, but not enough to give it all away. Well done on that.
I also love the way you wrote Freya and Charlie, they have this great sibling relationship that of course involves a lot of teasing and thinking the other is an idiot but it's obvious they do really care about each other. :)
The bit about the wand made me think too. Is that the unicorn that Voldemort killed in the Forbidden Forest during HArry's first year at Hogwarts? I think I know who has the matching wand though. Is it someone whose name starts with J and ends with 'ames'? :p
One thing that could use some clarification is that bit in the beginning - at first read I thought you meant that her mum is in her thirties and her dad in his twenties at the time the story is taking place, which confused me until I realised you meant when they got together - this might be something to clarify with just a few words - like maybe start the sentence with "When they met, ..." :)
Overall I think this chapter flows well. The end raised some questions for me though as I couldn't really understand Freya's motives for using hand signals. She's going to see James and co. in a few days anyway so is she just trying to delay the point when he recognises her? What is she thinking at this point? Something I think might make sense (though I don't know the specifics of Freya's condition so maybe not) is because she is going through PTSD from whatever happens, maybe she's having a sort of panic attack when James approaches? If that's what you were getting at here, maybe get into her mindset a little more and let the reader see what Freya is thinking/experiencing so it's more evident why she does what she does (if I'm making sense here.)
You asked if it's too cliche, and well, I've never seen anything like this before. The background of the OC is really mysterious and that's the main thing that stands out to me about the story. So I'd say that this chapter does not strike me as cliche at all!