Yes, the novel does a great job of establishing their interest in each other. I've finished the main story so I wonder how the manhwa is gonna develop those scenes. In the novel, a lot of Taekjoo's inner thoughts are described properly which helps you understand how he manages to handle someone as unstable as Zhenya. I'm currently reading the side stories and enjoying them a lot. The side stories are great for understanding their dynamic even better.
https://archiveofourown.org/works/72275911/chapters/188176636
Get ready for the crazy ride lol

Does the novel do a better job of establishing their interest in each other?
I feel like the two of them going from straight guys to interested in each other seems rushed? I get the physical attraction, and wanting to continue to explore something new that you liked (from Zhenya anyway). I still don't get how they're drawn to each other, other than physically.
The train scene where they end up drinking and laughing all night was a great opportunity it seems, but then it was just shown in overview.