Meet Persephoni! She’s a special “Elite” Guardian who has the ability to shapeshift into any form she wants — usually that of a small bunny. When she does this, she is visible to everyone (even those who don’t know that Guardians exist). This is how Chelsea is kept in the dark with the Guardians, and remains unable to see Seth and the others.
Also, Chelsea refers to Persephoni as “Pearl.” I figured since Persephoni never actually speaks to Chelsea, there’s no way for her to know the bunny’s real name, so she’d naturally call her something else.
Interesting fact: her character design has changed over the years since this strip was drawn. In this comic you can see how her hind legs were initially HUGE and her ears were much shorter.