It's been quite a while since I read one of this author's books but I remember them being more sophisticated than this, in particular the Gray Zone series.
'Seven' is essentially a comic book with no pictures and a lot more words. The villain is one of those über evil doctors that seem to have endless minions that never question the experimentation, torture and death that their cruel employer dispenses with hand-rubbing glee to the scores of innocent victims he keeps imprisoned. He even had female nurses who calmly and efficiently helped him carry out his terrible acts against young children. He was a completely unbelievable character to me.
The romance is insta-lust, where lust and good sex is equated with love. The two guys meet and seconds after an interesting introduction to the crazy Seven, they fall into some bewildering D/s sex and become bonded. WTF??
The whole storyline was manipulated by Nine (a disembodied 'Other') and I felt it deprived the other characters of a sense of 'agency' and self-determination.There was another secondary romance couple and several other young men who escaped from the lab who I presume will be the subject of future stories.
I didn't hate it but I wasn't that impressed.