General Opposites:
* Ally: This is the most common opposite, meaning someone who works with you or supports you.
* Friend: Similar to ally, but emphasizing a personal relationship.
* Supporter: Someone who actively helps you.
* Advocate: Someone who speaks or acts in favor of you.
Specific Opposites:
* Opponent (in a competition): This is a more neutral term than adversary, simply meaning someone who is competing against you.
* Partner (in a collaboration): This implies working together towards a common goal.
* Benefactor: Someone who provides help or support, often financially.
The best opposite will depend on the specific situation and the type of relationship you are describing.