Frankie is the plush bunny that appears in Dead End 1-13 in Paper Lily Chapter 1.
Frankie will sit idly in the facility's main area when Lacie and Sai return after defeating Miss Knives. Upon approaching it, Sai is unsure of what it is until Lacie points out it is at least trying to be a rabbit, Sai then calls Frankie an abomination before Frankie grows immensely large and presumably devours both Lacie and Sai and crudely chews them up. Frankie is the pet of the other Shadow person who makes a brief appearance within the facility (unlike Kat this one has a red outline to differentiate them).