Toxic relationship is in reference to a familial relationship. Also, in case there's anyone else out there that also gets freaked out by foreign objects going into someone's facial orifices,

there is a scene toward the end of the book where spectral bees are flying into Meg's nose, mouth, ears and tear ducts. Then a bit later in the chapter, they go into Apollo, and he says he can feel them ricocheting around his respiratory system. Meg's description is only one sentence, while Apollo's is few more lines.