These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Base Breaker: Either you like Salvatore and find him hilarious, or you hate him and find him the most annoying character in the series.
Godou and Athena, a lot. The first time they fought Athena kissed him. Granted the kiss was to apply a death spell but there was still other ways to kill Godou. Then after Godou allowed her to escape she became really eager to fight him again. Sorta like Salvatore actually. It gets to the point that even when she was dying her wish was to fight Godou. Godou himself mourns when Athena died in volume 9 and had a moment of silience dedicated to her.
Also Godou and Lancelot. Lancelot turned out to be a girl. When Godou confronts Lancelot she kissed him to apply a mind control spell. Granted her kissing him had a purpose but it was implied that she enjoyed it. Later when Godou snaps out of her control and fights her, she was a little to eager. Their dialogue was more similar to flirting at certain points.
Alec and Alice: They've been at each others throats since they were young teens, still bicker as if they were that age despite being 28 and 24 respectively... and show a surprising amount of respect and concern for each other.
Ho Yay: Godou has suspcious relationships with one of his past baseball buddies to the point where the girls gossip about it. Then there's his relationship with Salvatore. While Godou himself wants nothing to do with Salvatore, Salvatore wants to fight Godou really, really badly. To the point where when Salvatore was talking about there past fight, Liliana misunderstood and thought that the Italian campione was talking about a love affair with Godou.
On the girls side we have Sawa groping Yuri FOR SEVERAL MINUTES and praising her body.
Inferred Holocaust: What exactly happens when Salvatore turns modern technology off? Do planes drop from the sky? Do ambulances stop cold? Do pacemakers cease function? Hip or knee implants? Do cars keep their momentum, but lose their engines and brakes? This could get very, very ugly.
What Do You Mean, It's Not Symbolic?: In volume 13, Godou, Ena and Yuri escape from a battle by riding an improvised raft down a fairly vigorous river. To allow this to work, Yuri ties them together and to the raft using animated red thread.
Word of Dante: Due to a mistake on the part of an editor, Aisha was thought to be 1800 years old.