The first thing Eret notices is that Wilbur trades away as much of his shop homework as he can.
He's slick about it, and he makes sense. Eret's better at shop than him, he's better at English, why don't they trade?
The second thing Eret notices is that Wilbur doesn't test his song spells, not if he can help it.
After that, they start paying more attention. Wilbur runs from mals, but he doesn't cast spells unless he has to, and when he does they're often not ideal. Wilbur always does things by hand if he can, even when it takes twice as long, even when everyone else in the class casts a spell. Wilbur is obviously, painfully jealous of everyone around him, all the time. Wilbur's breath catches when he thinks he might have to use mana.
None of which is conclusive. But it's suggestive. And the thing it's suggestive of is that maybe Eret should get out of this group sooner rather than later.
They don't really know anyone outside it, nor are they as good at cold-approaches as Wilbur. But maybe the junior they sold Schlatt's drugs to will be able to help.
"Hello?"