Jason's words offended Johann, but the former didn't seem to care. He kept his gaze on Johann to see through him. He couldn't tell why, but he felt uncomfortable with Johann, and he wasn't blind enough to not notice how Avni was trying to set Johann up with Sonya.
He didn't know what Avni wanted to achieve by creating a rift between Sonya and Louise, and while he would have been excited to have Louise disappear from their lives, he couldn't turn a blind eye to Sonya's suffering.
He looked at Johann's body, assessed his physique, and scoffed in his heart. Johann had obviously let Louise beat him to a pulp to gain sympathy. Louise might be strong, but he wouldn't have been able to injure Johann so much if the latter didn't allow it.
This confirmed his suspicion that Johann had feelings for Sonya under the guise of friendship.
