I think you should read it at least until chapter 26, because by this chapter, the author has explained about why the prince acted like an asshole until now.
About the duke, he is not that scary. He's suspicious but nah, he's alright.
About the genre (psychological), i think it's because the knights are investigating a serial murderer case. Until now, there is no psychological romance or something like that.
Well, these are my opinions after reading until chapter 28 only. These can be wrong, but i think it's better for you to judge this yourself (because our taste might be different). After done reading until chapter 26, then you can decide whether to drop this or not.
So good luck on deciding!(づ ̄ ³ ̄)づ
p/s: I really hope i did not write any spoiler here. If you think i wrote a spoiler, i apologize in advance(/TДT)/
It's more of a mystery to me. Who's the father, and who's the killer. Everything else is just them being oblivious. It's hilarious. Maetel upset the Louis can't figure out that he likes him(for 10 yrs!). Louis neglecting Maetel advances because he got 'I got to find this killer' and 'how to dodge the Duke' on his mind. The Duke is fck'n crazy stalker. That's my take on it. Keep reading. Enjoy.(๑•ㅂ•)و✧
maetel is acting this way because of some reason. he's sulking because of that "reason" lol. don't want to spoil you so keep reading hehe. i really hope he'll treat louis better since he's been having it all his way.
and the duke? beware of him(;ŏ﹏ŏ)
i can say right now it's not really that toxic though. this was tagged as psychological maybe because of louis' line of work. our 2 mcs are good

im just on ch7, but i can say that maetel is not the kind of ML i like reading.. though i know it is still early for me to judge.. but i want to know if his treatment of louis will improve?
then i thought the duke was better since he seem to be the gentle and reliable type when he confessed to loui.. but then i read the comments and i got more scared lol or. i guess hesitant to continue..
in short, is this a toxic BL? the tags also say psychological so i want to confirm.. ( ̄∇ ̄")