Deepest Betrayal - Harry Potter

Harry James Potter, comes into his creature inheritance, and with that a whole web of lies comes undone. Who betrayed him who did not? (If you decide to read you will find out). Can anyone he thought trustworthy actually be trusted?

Book extract:
Harry pov:
I was lying on my "mattress" if that is what you could call it. in my cupboard, yes... they made me return to my cupboard, now that i am almost sixteen i barely fit. anyway back on track

I had just received one of my worst beating yet (at the hands of Uncle Vernon) for apparently not being grateful enough with barely and food and hand me downs. Merlin i hate him.
Anyway it was 30 seconds until my birthday and i was counting down.

29
28
27
26
Le time skip:
5
4
3
2
1

And then all i could feel was terrible pain this lasted for several minutes, but i had clamped my mouth shut so i did not receive a beating for waking up the walrus family, when that pain had gone i stood up and looked in the mirror.... holy shit!