Uncle/nephew. Age gap is 11 years. All characters are over 18. Kink/sex content (copied from the blurb):

incest, dirty talk (including use of female terms for male anatomy), bareback, cum fetish, D/s, sadomasochism, rape play, toys, gangbang, free use, piss play, prostate milking, somnophilia, dacryphilia, e-stim, voyeurism/exhibitionism, humiliation, ownership tattoo, orgasm denial/forced orgasm, cockwarming, medical play, enema/colonic, large insertions, gapes, male lingerie, and DP.