Recently discovered this podcast and wanted to share my thoughts on last night's episode.
The girl who swallows the frogbug is Sarah Palmer. According to wiki Sarah was born the same year as the White Sands bomb test, perhaps children of the atom make excellent hosts.
The frogbug isn't BOB, or MIKE for that matter, but some sort of mechanism for BOB to fully possess people.
The Giant creates the Laura orb and sends it to Leland Palmer in Twin Peaks as a means of countering and preventing BOB's influence.
BOB meets a young Leland who allows him to possess him rather than BOB possessing by force since Leland doesn't have a frogbug. BOB inhabits Leland and notices the Laura orb essence and gets a taste for her. His biggest challenge, to possess his opposite.
When Leland and Sarah have sex, the Laura orb is transferred to Sarah, and the frogbug can't coexist with the orb so it flees Sarah. The frogbug moves to Leland, making him possessable without invitation.
Sarah, having been exposed to the frogbug for so long, is able to see BOB as the frogbug made her body attuned to the spirit world.
BOB is unable to just give Laura a bug because the Giant's orb is part of her and protects her so he begins a campaign to break her spirit and the Giant's protection to a point where possession will be possible.
Somehow the Laura orb was split in two and we got Laura and Maddy which weakened the orb's power, and is why BOB was able to kill them both, and why both Laura and Maddy could see BOB.