Monster Stepbrother by Harlow Grace is a standalone dark romance with no cliffhanger and a happily ever after. 
 Maya is a sweet young twelve year old excited to meet her new step-brother the first time Oliver crushes her feelings. He is a sixteen year old, angry almost man who has recently lost his father and doesn't know how to process his anger. 
 It sets them off on a bad foot for the next few years growing up. 
 This story does have a few "convenient" plot twists that are a little beyond the realm of possibility as far as coincidences go but I enjoyed the way the story jumped from different ages to slowly tie each piece of the picture together. 
 I enjoyed this very much and am excited to read Quinn's story next.