This Jellal in Ch. 531
(I’m taking yonkou’s translation here because it’s very close to the raw’s meaning. He didn’t say anything near “That’s what I like about you” like mangastream has translated them; even though he must have thought that deep down but no he didn’t say it out loud here.)
I think it’s very interesting and well-written how Mashima wrote Jellal in this panel, commenting on Erza’s trusting personality. This not only shows how well he knows her, but is also like a follow up to Ch 416 where Erza questioned her ability to trust in people again and Jellal assured her she could.
Jellal appreciates Erza’s trusting personality. He knows it’s her good quality. But he knows it’s a weakness of her too because she can be used by people with bad intention. He is really the one who has numerous and different 1st hand experience in facing this side of Erza to understand why such personality is good but can be bad for her own at times.
She trusted in him to lead her to escape the Tower of Heaven when they were child slave. But he had exploited her trust in his good nature to deceive her that she had won and he was willing to die along with her in the Tower of Heaven (I’m talking Ch. 93 if you didn’t catch it). Then Erza showed her trust in him again in the Nirvana arc. When Midnight tried to talk Jellal in joining them. When she offered to stay by his side even she didn’t know if they would become enemy again if he regained his memories. When he showed up 7 years later with his memories back and as a member of small guide formed with his former partner in crime, asking for her help in investigating the GMGs, she agreed without questions. Then during Tartaros arc, her trust in the former Chairman resulted in her capture by Tartaros, and led to her self-doubting at the end of the arc.
So when Jellal says Erza’s trusting personality is a weakness of her, he is really like speaking out of 1st hand experience and observation. But he doesn’t judge or diminish her because this side of her had made her suffer. Jellal acknowledges once again, like in Ch. 416, trusting is Erza’s good quality, with another knowing smile. He doesn’t tell Erza to change, to be more skeptical about people, a true display of his trust in and respect for her.
I also really like how confident and honest Jellal is when speaking to Erza. He’s different from that Jellal who saw Erza as his light in Nirvana arc or that one who thought Erza was always right in GMG. He knows exactly where he stands beside Erza, not acting inferior to her, and is able to see Erza as Erza, strong but with weakness. This is character development.
Last I feel obliged to mention that this panel is perfect also because of his damn charming smile and that muscles under his tight turtleneck shirt.