from a sex freak angle, there's lots to love in the locked tomb books - threesomes (plural) with god, harrianthe armbone reconstruction sex, whatever tf was up with the nude paintings of valancy with the melons - but for me the single horniest thing is the wake pyrrha g1deon love/hate threesome situationship
imagine you're wake confronting your enemy on the field of battle & subduing her (a lyctor!) too only, before killing her, she wants you to kiss (& maybe fuck) her. you're so struck by this that not only do you kiss her, you spare her life & start crushing on her a bit
later you meet & kiss her again but it isn't her. its someone else living in the same body, a stranger fanatically loyal to the empire you've dedicated your entire being to destroying and now you're his lover too
and everytime you fuck him, you're also fucking her, your love who at some subconscious level can feel it too. you're split between love for her & hate for him, between overwhelming carnal lust & duty towards blood of eden
dios apate is kinky too of course (blasphemy is always profoundly sexy) but its here in the messy personal drama, the conflicting pulls of love & hate, desire & duty, the body swapping perversity that true horniness lies