Just like that one moment when ya are sleeping and then a person who you like and they like you sees you sleeping and tries to fix something but then ya wake up scaring them causing them to hit and run....??
When did Nozomi ever refer to Nico as anything but "Niccochi"? "You're one to talk" would definitely suggest the student council in my mind, so that just leaves Eli(especially given the calm nature of the comment).
Youmu and Reisen are both making possessive faces. Reisen giving the common "she's mine" look to the camera, but Youmu giving a "you're mine" look at Reisen. That definitely suggests an interesting dynamic between the two.
I think Youmu's expression is softer than it first appears, it's just her head being tilted down relative to the viewer makes it look like she's frowning a bit.