Do you really not understand the story? Yanek doesn't love Diesel. He wanted someone who's smart, strong, an assassin to be with him all the time who also has a weakness which he held onto. He could dispose of him anytime with that weakness. Yanek almost killed Diesel cause he couldn't tolerate the "thing" he bought, betrayed him. It's an obsession towards something he "bought" like a stray dog, nothing more. Ein wanted to save Diesel. Also Yanek's a human trafficker, drug lord, murderer etc... He deserved that..