What is even going on.. do I need to read the novel ?

if you want more details and cut scenes, it's in the novel. If it's this particular scene you are confused about, it will continue next chapter

Many people are commenting that the novel fleshed out Grayson's character better. That's why I am contemplating it

yes, absolutely. Since it was adapted by another author and artist, it was bound not to fully show the depth the novel author wanted to convey