He's usually calm however, as a half soul his personality takes a hit. The lack of memories from childhood causes him to start over during the child stage in a body more experienced than him. He becomes a lonely late bloomer with a dull personality that creates an inablity to come up with creative spells. At times he has episodes of being on autopilot which turns off his thoughts. His body moves on its own with its instincts.
His attribute seems very different to others especially when magic is neutral and depends on personality and thought processes. The reason that is is because Astuno is a special case. His seeing and hearing of souls isn't really magic but due to being half a soul. The gem in his chest blocks his magic from flowing properly and creates a lack of being able to control it causing him to think about it often and affects his magic.
Astuno's threads move smoothly but with the blockage, it stays mostly on his left side. He's unable to practice and train properly with it meaning he's unable to fight to his full potential. He fights to survive which thickens his thread and makes him stronger either way. His autopilot clears every emotion but stress and makes his thread tangle a bit and his magic a bit unstable. His body is athletic and under so much stress, his magic growth is impressive yet concerning.