Independent agent to provide author with advance we hear

• Sole holdout on a jury, perhaps
• Independent one
• Solitary sort
• One who shuns company
• Solitary person
• Person who's independent, much like a wild canine: 2 wds
• Independent sort
• Sort who doesn't hang with others

Wikipedia Word definitions in Wikipedia
Lonewolf is a French power metal band formed by Jens and Walkyr in 1993.