Blue emails Simon and writes that his New Year's was pretty slow. His stepmom and the wife of Mr. Sexual Awakening compared ultrasound photos, though Blue was grossed out by the 3D ultrasound picture of Mr. Sexual Awakening's fetus. In his reply, Simon apologizes for the fact that Blue is now scarred for life because of the 3D ultrasound. Simon says that he just got home from Target, where the Super Sharpies reminded him of Blue's love of superheroes. He also comments on Blue's unwillingness to exchange phone numbers.
The ultrasound pictures are symbolic of changes to come, and Blue's apparent willingness to engage with his family and friends as they look at the pictures suggests that he's reasonably willing to embrace this change. This could mean that unlike Simon's family, Blue's family may be slightly more adept at handling family members' changes.
Blue laughs at the superhero Sharpies and then says he's not ready to exchange numbers. He's afraid that Simon would call, get his voicemail message, and recognize his voice. Blue insists he's just scared to lose Simon. Simon replies that he won't call Blue if Blue doesn't want him to, but he just wants to text like normal people. He says he's ready for them to know each other in person, and asks Blue to think about it.
Being ready to know Blue in person suggests that Simon is becoming comfortable enough in his identity to make it known that he's not just gay, but is actually attracted to someone in real life. This would, notably, allow Simon to take control again of his own story and disseminate it how he chooses to.