LOL!!! That totally makes sense Mare!! Their bond is definitely intriguing to say the least, and the age difference definitely is a huge factor in it. Kevin the typical protective older brother, Howie the second in command peacemaker, Brian the goof ball who's just there, and AJ seems to be adapting more of a comforting role.
Case in point, the video of Nick messing up during "The One", and AJ making fun of him, but consoling him afterwards like it's okay; great homage to Nick being the baby of the group, lol. But, at the same time, seems like Nick has been calling shots, or taking control as of late; adapting more of a "I may be young, but the only one who can say shit or do shit to my bros if me; otherwise I'll deal with you." Lol.