Why dont people stand up for themselfs?

ok im 15 my best friend is freaking awesome! he gots problems expecially at home.. he gets picked on at school and at most the places he hangs out at hes not really shy he just dont take for himself. im a girl yes but i was rasied fighting and fighting back and i ve had his back thru tough ****, i cant do it anymore im pregnant :( i hate i cant protect him i love him to death you know he basically lives wit me now cuz his dad... dont awnser and call him a pu55y or nuthn cu hes not he just wont fight. whay are people like that?