
I think Jin knew he was being tortured and was going to "set him free" after he was mentally broken from Peter's torture and agreed to get a tattoo, so that he would end up staying. I'm not sure though, since we see that Jin (in the present) is still obsessed with Victor, I think he had a hand it in all along.

Just like Victor's sister did when she trapped him in that basement as a kid and "saved" him when Victor's dad came looking for him. Victor saw his sister as a hero and amazing for keeping him "safe" and "saving" him from that basement. (although he realizes the truth later).
Yeah, i definitely think that it would be hard for all that going on in Jin's house without his knowledge :(
I was confused as to when Victor would experience the Peter torture in the story, I guess now we found out but I'm confused as to why this would make sense, because he's not getting the tattoo anymore he's just gonna get tortured