Vali saw Loki playing with the emotions of the kid, taking pleasure from it. Honestly, he was feeling not so good playing this part of the treachery along with him but he was forced to do so as it was necessary for achieving their goals. He did not like the ways or character of Loki but right now he had no other choice but to align with him, all for the greater good of this world, for his objective.
He looked at the eyes of Orion as they lost their final spark when he heard the last sentence from Loki. Now he would be forever scarred by this incident. He shook his head as he finally couldn't take on his psychotic behavior of deriving pleasure from people's suffering anymore. He was about to stop him when he felt it first.
He felt his hair standing up as his breath quickened.
'He was coming !'