My real reasoning was that it's my chosen name, and my gender is male. But my parents pressured me more and more, and I was jumped into unexpectedly outing myself to my brother.
It's not all terrible, since I intended to tell him before I told my parents again anyway, I just wasn't expecting it to be so soon. Although, I've always worked best when I don't plan to do something at a specific time, and just go for it.
So I ran upstairs, and told my brother that if he opened the door and let me in, I'd tell him my Skype name, and explain myself because there was more to it. I was shaking so much, and he offered me a Rocky bar he had on the side, but I declined.
I decided to just go for it, asking if he'd heard of Transsexuality. He had! I proceeded to gesture at myself shakily. He pulled me to sit next to him, hugged me, and took hold of my hands, telling me that it didn't matter to him at all, and it was fine. He seems to think I still like women, though, on account of him thinking I crush on Scarlett Johansson. I wouldn't mind if I did, she's a beautiful woman, but I'm kind of gay and with a woman, anyway.
Turns out, he saw the same documentary that I did, the one I wrote about a while ago. 'Boy Who Was Born A Girl', so he understood, and just asked my name. True, he proceeded to laugh and ask why, so I explained everything except that I got the name from Vampirates, a damned awesome book. He told me to give mum and dad time, because it's not that they don't agree with it, more that they can't believe it's happening to them, to their little girl.
Me and my partner knew my brother would be a good ally, and I'm so happy that he knows now. He guessed about my relationship too, but doesn't believe in asexuality. I still reckon it's linked to my dysphoria, but it's all well and good.
It was spur of the moment, and I don't know quite how it happened, but it's a good sign and if telling my parents goes badly, I'll just go to him about it.