Oh well i don't ship them that much i see them as this siblings who would get in the other's neck frecuently but still care about each other nevertheles.
I love the bonding momments they have because they stablish well how their frienship works with a sassy cass that bickers everytime she gets the chance and a Eugene that would just fire back as well.
I can see chemistry as in a love-hate relationship but they have the siblings rivalry energy more.
So after all this have been said i will give it a 7.1 because is just possible in AU where new dream doesn't exists :")