Lyric discussion by Love is suicide... 

Cover art for Spaceboy lyrics by Smashing Pumpkins, The

Got this from blamo.org:

This is a song on Siamese Dream. Billy wrote this for his little disabled brother, Jesse. It's a very quiet song also.

Here is an Article about Spaceboy and Billy's Brother.

Here is what Billy said about Spaceboy. "That’s about my little brother. He’s an interesting character. It’s kind of about how he’s different. He has physical handicap, it’s hard to explain. He has a rare chromosomal disorder, it gives him a some what different genetic make up. He has different physical and mental problems and yet somehow by all accounts, I’m physically and mentally OK. But I feel our lives are the similar. (Similar in the way that we are both) Freaks of nature, freaks of society, I always keep going back to something by Henry Miller. No matter how much he smiled, told jokes, shook hands, patted people on the back. People still looked at him funny, they still sensed something wasn’t right. I’ve always felt that way, that no matter how normal I appear, I was treated differently.