Ah, here this page is. While gathering these pages for slaying material I've been halfway rereading them (obviously, as I've been commenting on them), and I'd been wondering if I hadn't of somehow missed this page.
Well... that was unexpected, but maybe he understands Rain and might help her, it does open up a lot of possibilities now doesn't it. I love Rain's face in the last panel its like oh crap. And it looks like Brother Arthur is smarter than we thought.
Brother Arthur uses his rectangular glasses of truth to stare into your very soul and bring to light the secrets that lurk in the shadows...
Seriously, though, this page really comes as an immense shocker! I never would have guessed that Brother Arthur had an ftm sibling. This revelation adds interest to Brother Arthur's character, beyond the "nice teacher" archetype. In addition, it marks the fourth transgender character known to exist within the comicverse (following Rain, Kylie, and the "friend" Aunt Fara briefly mentioned in chapter 2). The fact that Brother Arthur a)even brings up this story, and b)asks Rain in particular if she is "familiar with this concept", suggest that he suspects Rain of being transgender. Rain detects the inference, and is terrified at the thought that her secret may have been discovered.
Why is Brother Arthur doing this, and what is he planning to do? Clearly, he is testing the waters about his suspicions of Rain, to see if there is truth to them. As he mentioned at the start, though, he doesn't want to pressure Rain - if Rain doesn't want to open up, I don't imagine he'll force her to. While it's possible that Brother Arthur is trying to dig up information to blackmail Rain, or get her thrown out of school, that would go against the sympathetic persona he has cultivated. More likely, he's letting Rain in on his own secret so that she knows she has another adult at school with whom she can talk about her problems. He's doing the saintly thing, offering to help one of those who has the greatest need for support. Again, he shows that he genuinely cares for his students.
The events of this page happening at all, though, hinge upon the question: what has caused Brother Arthur to suspect Rain of being transgender? Perhaps his history is enough: growing up with a sister who wanted to be a man, his transceiver became very sensitive. There is, alternately, the possibility that Aunt Fara told him; given how important keeping Rain's secret is to her, though, this possibility is remote at best.
If there is anything unfortunate about this conversation, it's that Brother Arthur's announcement, directed at Rain, drastically overshadows his interaction with Rudy. The pain and disgust Rudy has to undergo while claiming to have been "cured", to hide who he truly is, is very much apparent. Brother Arthur, though, recognizes it as a lie, making him the first person at the school (outside the main cast) to know it to be a falsehood. In saying "You don't have to lie to me, Rudy", Brother Arthur is not making an accusation, he is offering an invitation. He also wants Rudy to trust him, to know that there's an adult at school he can go to and be genuine about his problems. Yet again, Brother Arthur plays the saint.
A rather shocking page, that brings to light new details about a minor character. Certainly, Rain and Rudy's relationships with Brother Arthur won't be the same after this conversation.