
Umm... i've been calculating their ages and the math isn't looking so good

The servant said it had been over 10 years since he started archery, and he started at five, so let's say that he has at max, 17 years now. Because how far "over" 10 years can it be? 2 years? 3 years? Still, if he has the same age as his uncle in that time, let's say 17-5, they have a 12 years age gap, so his uncle must be in his late 20s
Honestly, this could have been a good thriller BL if the author wasn't just throwing random fetiche stuff around, and actually knew how to write. The premise of giving up and becoming as corrupted as the villain, who you swore to never be like, somehow reminds me of the ending of Hannibal, when Will finally embraces his twisted nature and brings him and Hannibal to an end. Still, I like that it didn't end up as a romance, so you can catch that it wasn't supposed to romanticize the ML's actions.