Apologetic Attacker: Kayka actually apologizes to Soto after the Eye Scream she performed on him (See Below). However Soto doesn't believe she is actually sorry and says so with Kayka readily agreeing though it is unsure how sincere Kayka was being.
Batman Gambit: Kayka's plan to get Diego together with Sid is so that she would no longer have any hope of being together with Diego. Slightly subverted in the fact that only the first part works, not the second.
Also the Gods plan to force Kayka into a job as punishment for breaking all of the rules set on her to be able to go back to the earth. The funny thing is Kayka knew about it and did it anyway.
Bittersweet Ending: Sure Diego gets a mate and is potentially set up to have a Happy Ending but Kayka on the other hand is stated to have willingly destroyed her own happiness and has been charged into doing a job that is heavily implied to be unpleasant and possibly damaging.
Brother-Sister Incest: It is revealed that Kayka is actually Diego's little sister. This reveal is made after Diego seriously considered making Kayka his mate as well as several intimate scenes between the two including when Kayka 'kissed' him. This is even worse when you realize that Kayka knew that Diego was her brother all along and has even blatantly stated to two separate characters that she is in fact in love with her brother.
Chekhov's Gun: Kayka's blue eyes which are the major hint that she is in fact dead considering she died before her eyes could change color and is what Diego questioned her on which tipped him off on Kayka's true identity.
I Have Many Names: Kayka seems to be headed this way considering she gave up her true name 'Kara' when she died and then gave up 'Kayka' at the end of the story because it reminds her of too many good memories. She now wants to go by 'Kona' which apparently is a short, feminine name for 'Conniving'.
I Want My Beloved to Be Happy: Subverted. for even though Kayka did set Diego up with Sid it was not because she wanted Diego to be happy though in her words it 'was a bonus to the whole plot' but because she wanted to make herself miserable.
Matchmaker Crush: Kayka who is in love with Diego while she tries to hook him up with another guy...
Meaningful Name: Kayka's true name 'Kara' means 'Beloved' which Diego named her for being her Mother's 'beloved' daughter. Also Kayka's new name 'Kona' is apparently a shortened version of conniving which is Kayka's most distinguished attribute.
Parental Abandonment: After his mate's death Diego and Kayka's Father abandons Kayka because he believes that Kayka is responsible for his mate's death.
The Powerof Blood: Type A. Kayka feeds her dead blood to all of the members of Diego's herd in order to bind them to her so that not only can she be the only one of the dead world to touch them they get a portion of her lost years and Kayka gets to lead their souls to their judgments.
Promotion to Parent: Diego is implied to become this to Kayka after their father decides to have nothing to do with her after his mate's death.
The Reveal: Two! One that Kayka is in fact dead and the other that she is Diego's dead little sister.
Say My Name: After Diego realizes who Kayka actually is he all but screams her real name 'Kara' for several minutes.