Because this two stories crossover and intertwine you might want to read the other to get the context of what happening in Such A Little Jinx at some points with the story and characters.
Remember Happy isn’t a normal fluffy, she’s a Hunting Friends (or a sentient ball of fur that grew into a fluffy shape that craves meat and like horror and jellens) and was made in a lab. She, and her kin, follow their own set of rules.