Brethren, Brothers, Fellow Countrymen, Compatriot
noun
People who have the same cells as you are your brethren, they're your brothers!
どうほう, どうぼう
This is a jukugo word that uses the on'yomi readings of the kanji. You should be able to read this on your own.
お前は同胞を裏切るつもりか。
Do you intend to betray your brethren?