Sam might not know this, there is a message behind the posture of the soul form. Particularly Dormant soul which is the accurate clone of the emotions and memories with no actual free will. Its form would be instinctual and it represents their mindset.
Sivan's form which is a man huddling himself is a symbol of fear. He clearly knows that, but every soul he has seen until now, are always worse than him, there are few that are a bit better, but they are all weak.
This is the first time, he saw a soul as strong as him or even stronger than him, but have this kind of posture.
The soul looked like it belongs to a man who can take on the burden of the whole world solely on his shoulders without a second thought.
He gritted his teeth and tried to probe the soul.
The Ghost Chimera that sensed the activity against the soul, immediately targeted Sivan's soul, all the faces made their way towards him as they roared soundlessly.