Noctis hadn't moved when the boy first spoke, he didn't need to, the bastard Tristan wasn't talking to him. His words, all sharp with theatrical venom, were aimed at Oliver.
He never really knew the point of Oliver existence in the first place, in his first life he never really acheived anything. Apart from losing control when ever he used his Art.
While until the conspiracy around Vermilion clan was revealed. The boy actually merged with a piece of a mad celestial flesh, granting him mind blowing powers.
'Troublesome'. Oliver was troublesome because he knew he would be killing him in the class next semester test. He would loss control and he would be the one to put him down.
He wouldn't allow him to rampage and kill Camila just like in his past life, this time no more hesitating. Camila was too critical for his plan.