It's been a long time since I made this post but I will try.
Primary point being that everyone is capable of learning and changing and this applies to feelings or emotions as much as it does opinions or beliefs. Emotions and feelings play heavily off of one another. Even if Asura initially felt only fear, as time went on, he would naturally experience more things besides fear. The world around him affects him as he doesn't exist in a vacuum.
Let's say he only felt fear. But being around others eventually creates a sense of familiarity and stability, things that can help alleviate that fear and provide comfort. And that leaves room for some kind of attachment, care or fondness. But Asura doesn't understand this concept. He was made as a whole person, and he's suddenly having all these foreign things forced onto him. Its scary because it's new and unknown. It's overwhelming.
The emotions he grasps quickest would be those like fear or those that would cause him to feel fear. Like unease or suspision. These are natural to him. And for the latter, anger or disappointment would likely make him more afraid. However concern would also be natural for him to feel, born from a fear for other's safety regardless of the reason.
Ultimately Asura is a being of fear, he's driven by it. Fear is a core part of him, something that cannot be taken away from him. It's his motivation and will always be. But if he could have learned to cope, to express those fears in a safe enviornment and to trust and confide in others, he could have been much more than the fear that made him. It would never go away and would always play a part in his choices but it wouldn't have to control him.
We know he can feel other emotions. He cracks a fucking joke when he wakes up for fucks sake, man's got a sense of humor. He shows he's prideful but self aware, confident in his own power as a kishin and likely somewhat before. He expresses annoyance, anger, frustration, so on and so forth. He can feel more than fear.
If you want to know what I think his life was like before becoming a kishin? I'd say he's a victim of neglect. Severe neglect and maybe emotional abuse, regardless of how intentional it may be. Being "born" as a whole person meant being expected to know everything someone of his percieved age should know. Being made of fear meant not having anyone who understood the way he thought or felt. And it's not uncommon for people to shun what they don't understand.
Death himself may have avoided Asura like a plague as he made Asura to get rid of a part of himself he didn't like. When Asura's fears got in the way of... Anything. Well I can imagine Death would be frustrated by that and moreso if it reminded him of the things he disliked about himself.
I think humans generally shunned him. People he should have been able to rely on avoided him or simply didn't care. There was little to no support system for him. He had few positive examples and a ton of pressure and expectations hanging over his shoulders. And I think he hated it. Hated his fears. Hated himself. Hated that he couldn't be "normal". Feared his own self loathing. Got stucknin a loop of it until he drowned in his own fears to the point he was willing to commit atrocities to get rid of those feelings.
Like. If this were the case then Asura is a pitiful character. A terrible person yes. But still pitiful.
