Fultheim the Fearless is one of three hostages during the quest "With Friends Like These...." He is a mercenary who was captured from a battlefield. He does not have any ill thoughts against anyone but many people would definitely put a contract on him due to his occupation that involves killing many people, the relatives of the victims may have a grudge against him.
He is one of three possible murder victims after the Dragonborn is abducted by Astrid and brought to the Abandoned Shack. If Fultheim is killed, Astrid congratulates the Dragonborn with, "Oh ho. The whimpering Nord, eh? Yes, yes, I can see how you'd come to that conclusion. Interesting choice."
Despite his name and occupation, Fultheim is quite cowardly. He constantly fights back tears and begs for mercy while you interrogate him.
"What did I do? Please, whatever it is, I'm sorry."
- Who are you? "My name is Fultheim. I'm a soldier. Well, mercenary, really. You know, a... a sellsword. I've lived in Skyrim all my life. That's all! I'm a nobody, really. So can't you just let me go?"
- Would someone pay to have you killed? "What? Oh gods, I don't want to die..."
- Answer me, or die! (Intimidate) "Please! I don't know! I mean, I'm a soldier. I've killed people. When I was ordered to. Maybe there were some times... some times I got carried away? But war is war. Right? Nobody could blame me for that. Could they?"
- Shhh... Don't be afraid. You can tell me. (Persuade) "Okay, well... I guess it's possible. I've been selling my sword arm for years now. Killed a lot of people. Could be someone wanted revenge. But... But you're not going to kill me. Right?"
"Please! Release me! Cut my bonds!"
- (Cut the captive's bonds) "Thank you! Thank you! I'll never speak of this to anyone, I promise!"
"Thank you! Thank you! I won't tell anyone what happened here, I swear it!"
- "Is this about that raid last week? I told Holgrim there was no honor in killing sleeping men, but he wouldn't listen! It wasn't my fault, I swear!"
- "I... I can hear you talking out there. Please, let me go. I've done nothing to you."
- "Please, oh please, I don't want to die..."
- "Oh, gods, please! Let me live! I'll do anything you want!"