Stark’s Fracción is Lilinette, a female arrancar who seems quite mischievous, in that she enjoys waking Stark up in unusual ways: first by shoving her fist in his throat, then by squeezing his testicles. Despite her initially childish behavior, she does seem to show some concern for the ominous occurrences in Hueco Mundo.

(Source: Bleach official character book III)