Jonah thought he wouldn’t feel anything after losing Barnabas that he doesn’t care that he can sacrifice him to satisfy his curiosity… In the end he was suprised that Barnabas’ death really hit him…

On the other hand he expected that lost of Peter would make him feel something. Yes their relationship was always a one of convenience and all the feelings were just a performance for sake of it…. But somewhere deep inside Jonah thought it will - it might make him feel something. He was genuinely suprised how indifferent he was towards Peter’s death. He was even a bit disappointed by that. He hoped to feel something again…