Honestly, I discovered the first book of the Interstellar ABO quartet only after finishing the third one. Initially, I read it out of curiosity about the parents' story, specifically Lin Yuan and Xi Zhe, or Caesar. Now, I'm left with mixed feelings that I can hardly express. I should've known better, as I even read it despite the reviews.
While I appreciate the bond between Brian and Snow, as well as Lin Yuan's parents, I just can't connect with this particular couple. Here's a spoiler:
Lin Yuan's identity was concealed because of not wanting to upset someone and disrupt their worldview. However, the lack of consideration for his vulnerability without suppressants, potential exploitation (like Caesar), and the development of resistant alpha pheromones that would require military service is frustrating. Additionally, how could the military accept him if no omegas were allowed? There might be a reason for it, like an omega going into estrus during a conflict.
The relationship between Lin Yuan and Caesar doesn't appeal to me anymore. The third book, featuring Luo Fei (the main character from both books) and Mo Han, stands out as superior. Luo Fei is a great alpha, albeit occasionally careless, and Mo Han is more active in their story. Their marriage setup was fantastic, too.
In the third book, Luo Fei and Mo Han faced similar challenges but had a mutual love and understanding. Mo Han was in estrus, and they were in a dangerous situation, but Luo Fei refused to mark him without explicit consent. Even then, Mo Han's persistence led to a heartfelt connection.
Luo Fei and Mo Han's relationship is leagues above what we see here. Even Mo Han's parents' relationship doesn't measure up.
As for a minor spoiler, Lin Yuan's brother Ling An ends up with Brian's younger brother in the future.
I genuinely recommend starting the Interstellar ABO series with the third book, "Interstellar Marriage Guide" (untranslated; search for it on translation sites), which focuses on Lin Yuan and Caesar's first child, Luo Fei and Mo Han. The fourth book, "Film Emperor's Secret Marriage" (translated), delves into Luo Ning, the second prince, and the film emperor, and promises to be a better introduction to the series.