In Swamp Thing 50, Swamp Thing basically convinces the Great Evil Beast not to invade heaven by answering it's query about the purpose of evil: Swamp...
I recently reread the American Gothic arc of Alan Moore's Swamp Thing and I realized how more effective it was as a political commentary than so many...
In regards to pet characters in comics, most of the examples I can think of are created by the people who flaunt them such as Bendis with Naomi, Marv...