Recently my brother has taken advantage of me. I changed my behavior and attitude to being good. I've been helping him out and doing stuff for him sometimes. I just wanted to see a change in him. But he's taken advantage of me and he's making me do everything. That just makes me very angry, and I don't think I can take it anymore. He's older than me. Should I stop being good to him?
"And just as you want men to do to you, you also do to them likewise. But if you love those who love you, what credit is that to you? For even sinners love those who love them. And if you do good to those who do good to you, what credit is that to you? For even sinners do the same. And if you lend to those from whom you hope to receive back, what credit is that to you? For even sinners lend to sinners to receive as much back. But love your enemies, do good, and lend, hoping for nothing in return; and your reward will be great, and you will be sons of the Most High. For He is kind to the unthankful and evil" (Luke 6:31-35).
It might depend on what you see as "doing good" for your brother. Something might appear to be good and is not good for a person. For instance, you might do your brother's math homework for him. It might appear to be doing him a favor, but you would actually be doing him harm because you would be preventing him from learning.
But assuming that what you are doing is actually good, then you should do such things simply because it is the right thing to do and for no other reason.