Over-the-top caretaking triggered
Overall, I loved the characters and story, so my issue is the exact opposite from most who didn't find this story appealing.
Despite the author's bend-over-backwards efforts, I couldn't suspend disbelief enough for the utterly submissive's first-ever sex to be heated instead ultra squicky to me. So much so it made the whole experience rather negative - basically a trigger. The sex fit the character perfectly, just not for someone who had zero experience (apart from one hand job?).
I loved Patrick’s character, and Seth’s patience and control outside of the BDSM scene.
The fact that Patrick was an utterly untouched virgin (one hand job only) made his initial sex scene (paddling, bound, rough screwing) very squicky/triggering rather than hot to me.
I’m very (often overly) sensitive about BDSM and how I was taught to practice it, so my issues aren't often shared by other readers. But for me, despite the author’s best efforts to address safety (safewords, extra safe equipment, Patrick begging for it), I had significant issues with that scene, which are mostly about me suspending disbelief about my technical experience, training and practices.
(E.g., reliance on newbie use of safewords, how fast to introduce equipment, allowing a new sub to drive/topping from the bottom, and, most especially, how to prep and take an utterly virgin butt, especially on a guy with zero other experience, first experience in BDSM vs. vanilla)
On the positive side, the book explores a situation when a very submissive personality called upon to be the firm, strong, and especially the leader everyone depends on in daily life, and how that manifests in the need to be even more submissive if the opportunity ever presents itself. (It's a similar but different dynamic/mirror of the CEO Alpha who needs to a safe environment to submit. Both are about people who need to give up control - to not be in control but depend on somebody else - but can't do so in most/all of their daily lives.)
This "submissive in a responsible leader's clothing" no doubt triggers an even strong caregiver Dom response in Seth. In that way, the depths of Patrick's submission and Seth's strong response make sense (while being very over-the-top and rushed compared to likely real life developments for the sake of the flow of the fiction). It just hits that trigger where the shortcuts and speed for the sake of a concise story hit that "oh hell no" trigger for me.