A 1cor6 brother is someone that takes is brother to secular court or calls the cops on his brother. It could be a doctrinal disagreement but it could also be something else.
The right way to deal with a brother trespassing against you is in Matthew 18.
1 The Corinthians must not vexe their brethren, in going to law with them: 6 Especially vnder Infidels. 9 The vnrighteous shall not inherite the kingdome of God. 15 Our bodies are the members of Christ, 19 And Temples of the holy Ghost. 16.17 They must not therefore be defiled. — KJV, Chapter summary 1 Corinthian 6
 Dare any of you, having a matter against another, go to law before the unjust, and not before the saints?
 Do ye not know that the saints shall judge the world? and if the world shall be judged by you, are ye unworthy to judge the smallest matters?
 Know ye not that we shall judge angels? how much more things that pertain to this life?
 If then ye have judgments of things pertaining to this life, set them to judge who are least esteemed in the church.
 I speak to your shame. Is it so, that there is not a wise man among you? no, not one that shall be able to judge between his brethren?
 But brother goeth to law with brother, and that before the unbelievers.
 Now therefore there is utterly a fault among you, because ye go to law one with another. Why do ye not rather take wrong? why do ye not rather suffer yourselves to be defrauded?
 Nay, ye do wrong, and defraud, and that your brethren.
 Know ye not that the unrighteous shall not inherit the kingdom of God? Be not deceived: neither fornicators, nor idolaters, nor adulterers, nor effeminate, nor abusers of themselves with mankind,— KJV, I Corinthians 6:1-9
Its vexing your brother to take him to secular court or call the cops on him. We should of course forgive him but not necessarily continue having anything to do with the brother. We could take it up with the saints .
Its defrauding your brother to call the cops on him or take him to secular court . Its an act of unrighteousness to do that and the unrighteous shall not inherit the kingdom of God .
Though I would say that this is a common thing among Christians. That they call the cops on a brother. It is especially common in churches that someone calls the cops on a brother.
What shall we do with these people?
They are not your brother . Look upon them as people that shall not inherit the kingdom of God .
There is no point having fellowship with people that claim to be christians are are not.