
1) The people on his phone was prolly from the times where he had to substitute for his father cus he's not well. Like the old guy from the 1st chapter that he slept with. He also mentioned how he keeps those guys in his father's "favour"
2) The guy stalking him was most likely his father. I mean, he had a gps, private investigator, and followed him arounf with a car. Not sure tho.
3) Ever since he was a child, he felt like everything was his fault because of his mere intervention, his existence. So I think he developed a passive personality, the most not invasive and invicible personality, so that he doesm't "ruin" anything anymore.
4) Just like what the uke said, "it's easier to just flow with it" + also ppl respond and cope with trauma differently. Pretty hard to see a way out when all you have is your father and the pressur(๑•ㅂ•)و✧e of the country in regards to your father's title of "renowed author" + his mother also noted on him to "take care of his father" so with that and his passive personality, his situation ultimately led to that.
This is such an amazing manga that I found myself enjoying and dissecting parts aaaaa and I found your questions to be enjoyable

I just reread this 2 years later because I forgot the plot when you replied, and I have to say that my enthusiasm for this manga... has changed a lot. I mean, it's an okay read, but damn, my reply from 2 years ago felt like I saw this as a masterpiece lmao. Looking at how it ended, I'd say that IS pretty rushed and incomplete, and a Volume 2 to really flesh out the development would've been so much better.
I mean,,, who were those people on his phone? Who was the one who stalkered him? Why the uke was so passive? Why the uke didnt even try to escape? The author knows the fact that the only way to have a good ending here is the death of the father