Talking with Farkas can get you these quests.
Any city in a hold you have visited.
This can target almost any of the citizens spread throughout Skyrim. Because of the mutable nature of the game, it is better to quickly complete this quest so the NPC does not die to an event before the Dragonborn can defeat them.
When you find the target, have any followers wait in a different room. This is to avoid them interfering with the brawl. During the brawl, you cannot equip any weapons or use any Shouts.
Winning the brawl improves the disposition of the target toward the Dragonborn.
Killing your target decreases your reward.
- Level 1-9: 100
- Level 10-20: 150
- Level 21+: 300