You could just read it in the novel, just that part.
https://novelingua.com/desire-me-if-you-can-chapter-069/
Scroll down a bit.
Grayson is a psychopath he has no emotions in any shape or form every emotion he had to be taught how he must react! So this situation was shocking to him cause he never saw it coming and the thought of something unplanned going on freaks him not to mention he wanted dane cause he was fierce and he wanted to basically break his ego somehow so the fact that dane jumped him confidently didnt suit his end goal!
He has emotions, he always had. The problem is that he is unable to recognize them in himself. In real life it could be discribed as a heavy case of Alexithymia.
The only thing Grayson wanted at that time was seeing the "butterfly".
But the situation, as in Dane, got out of controle. He was shocked and panicked. He didn't want to get forced by Dane pheromones.

I love how its typical that an omega will get their heat and the alpha would force them but theyd be like i love him its okay and thats their relationship start but how funny it is that all grayson was wanting is to get it with dane but the moment dane jumps him hes scared for his life im very excited for how his face will look like cause thats funny as hell