One time when i was younger, like 8, my brother asked if i wanted to see his penis i said no but why would he ask something like that?Did u think he wanted to do something with me?

At that age kids are curious. He had probably been exploring his body and wanted to share it with you. As for weather he wanted to do something with you, it is possible. Sexual experimentation is common with kids that young, especially with a sibling. I wouldn't be worried about it though. Usually this kind of stuff is very innocent. It is most often more of a learning experience than a sexual one.