In Absalom's case, he conspired against the Lord's anointed, David. Ultimately, Absalom lost. David was successful in outlasting Absalom for two reasons: 1) God was with him and for him; and 2) he was self-aware of what was going on around him. When he was criticized by someone from Saul's clan, he permitted the criticism. He said, "Who knows if the Lord told him to say this?" David knew that some criticism was justified and valid...and this man went straight to David with his criticism; he did not form a conspiracy.
In Matthew 18, Jesus taught us not to conspire with others against an enemy or build ourselves up at their expense. Rather, he taught us to go to the one who wronged us and work it out by talking to them.
If you find yourself refusing to talk to someone you have a problem with directly (indirect forms of communication such as letters and emails do not count) you may be close to committing sin. Be careful not to conspire or to triangulate others in to your problems with another. As Jesus taught us, love God and love your neighbor as yourself.