Related Clues:

• Friend alternative
• Hostile opponent
• Armed adversary
• One of them?
• The Riddler, to Batman
• Sworn enemy
• One on the other side
• David, to Goliath
• Bizarro, to Superman
• A McCoy, to a Hatfield
• One to go up against
• One against another
• Axis, once
• The other army
• No proponent