'Brother' in the Bible

Paul, an apostle of Christ Jesus through the will of God, and Timothy our brother, unto the church of God which is at Corinth, with all the saints that are in the whole of Achaia:

I had no relief for my spirit, because I found not Titus my brother: but taking my leave of them, I went forth into Macedonia.

And we have sent together with him the brother whose praise in the gospel is spread through all the churches;

and we have sent with them our brother, whom we have many times proved earnest in many things, but now much more earnest, by reason of the great confidence which he hath in you.

I exhorted Titus, and I sent the brother with him. Did Titus take any advantage of you? walked we not in the same spirit? walked we not in the same steps?