Even though they hate marl, this is exactly what he did to me constantly.I can only imagine the kinds of conversations they have and anything Opa is unsure of, Glip and Eevee are there to set him straight.
I don't want to be too specific, but the topic of beastiality came up and I actually told marl it made me sick and scared (for specific reasons), like extremely so because animals cannot consent.
He replied that animals consenting is a gray area, but there are definitely signs if they don't want it so it's fine
He was Glip's husband back then and Glip had been a fave artist of mine at the time... so I didn't want to disagree, and besides he spoke so calmly and like such an authority that maybe he was right and I just hadn't thought of the issue of animal fucking enough
This opened the floodgates. he talked about animals (dogs included) any opportunity he had. He said he was very sexual, much more sexual than Glip, and Glip did not satisfy him.
He said this all casually. Even if I gave lukewarm responses to toe the line between disagreeing and agreeing, he would keep talking until I agreed on SOMETHING or other
I do believe that Glip does not like to get fucked by dogs (hence Marl's need for more people) but I feel that Glip had to have known of his tendencies. At least have had an inkling of suspicion. I can't imagine that he can get fucked by a dog so silently like a ninja for years that the other two didn't notice.
This is all to say I don't doubt opa-opa is being preyed upon. Even if it is not as (seemingly) devious as marl, I feel sympathy for him as I had been there once before.