_Happy Death Day_ succeeds largely due to Rothe's engaging performance, reminiscent of classic scream queens. The supporting characters aren't as developed, so a great deal of responsibility rests on her shoulders to portray a believable central figure. As the protagonist, Tree has to be captivating enough for viewers to tolerate the story’s repetitive elements, but also adaptable so that her character can evolve. A noteworthy aspect is her connection with Carter; it needs to develop within a single day for him—since he doesn't remember each reset—and simultaneously demonstrate advancement for Tree across her multiple experiences of the same day. The dynamic has to function as both a fresh start and convey a sense of progression at the close of every repeated cycle. Broussard and Rothe effectively establish this from their initial scene together, with Tree waking up disoriented in Carter’s bed.

Source on TMDB