Reborn as the female lead's twin brother Reverse harem x male reader RATFLTB

M/N opened his eyes and found out he had being reincarnated as the female lead's twin brother, in the R21 omegaverse novel series "The lady's survival" he had read in his past life as an over worked office man. The only problem is this. The female lead never had any siblings, and the dark messed up world of the novels plot was not exactly his cup of badly made coffee. How badly has he messed the already chaotic plot up ? And how the heck would he be able to survive.