Ten possible roles

The 'third side' is the person on the sidelines in a conflict who wants to help. Third-siders can be neighbors, neutrals, bystanders, family, friends. Event the warring parties themselves can take the third side. This book describe ten roles that this person can take.
Their goal is always to prevent conflict before it happens. Even the presence of a third person will calm conflict, but doing nothing does not optimize the help they can give.
Three strategies (and roles within each) are offered to manage increasing levels of conflict: 
 * Prevent (Provider, Teacher, Bridge-builder)
 * Resolve (Mediator, Arbiter, Equalizer, Healer)
 * Contain (Witness, Referee, Peacekeeper)
1. Provider
When there is conflict is often over scarce resources the Provider finds ways for both sides to get what they need, even deep needs such as love, safety and esteem. They can also provide knowledge to enable intelligent decisions.
2. Teacher
People often fight because they know of no other way to resolve
their differences. The Teacher shows them how to handle conflict without resorting to violence and arms.
3. Bridge-builder
People in conflict often become separated by deep divides which lead to ignorant stereotyping, etc. The Bridge-builder builds ways across the dividing chasm, for example by building trust, showing how the others are human too.
4. Mediator
Where there are conflicting interests, the Mediator tries to bring them to the table. If this fails, they use shuttle diplomacy, going back and forth. Sometimes a higher authority may be able to coerce them to the table.
5. Arbiter
When there are disputed rights or when mediation fails, the Arbiter acts a judge and selects a final solution, to which both parties must agree to be bound.
6. Equalizer
Where there is unequal power, the powerful may not seek help but the powerless deserve it. Their position of greater power may cause the powerful to rethink and bring them to the table.
7. Healer
Injured relationships can fester if left alone. The Healer seeks to calm emotion and soothe hurt, for example by listening and acknowledging within a climate of healing.
8. Witness
When nobody pays attention, atrocities may be committed. The Witness needs only see and tell the truth. Just by their presence, they may also dissuade the wrong-doer.
9. Referee
When people resort to conflict without rules, people get really hurt. When you cannot stop them fighting, the Referee at least sets and polices the rules.
10. Peacekeeper
Where people are completely vulnerable, they are open to easy attack. The Peacekeeper provides safety for the victims, interpose themselves between the warring parties and enforcing the peace.