From Potioneer to Berseker
Prepare to say goodbye to these herbs you call your friends and this lab in some days. And remember the name that will be the reason behind your ruin. It's Sienna Slughorn!"
Sienna slowly left the lab after declaring her threat. Eren had understood that his refusal would have repercussions. But he didn't understand the severity of them at the time.
Sienna had ties with the potioneer in charge of the first years. He would be a mad potioneer not to form ties with anyone from the viscount Slughorn's house. He was the reason Sienna could dump her assignments on Eren without anyone being the wiser.
The potioneer in charge couldn't control everything that happens in the academy. But the first-year lab was his domain. He might not be able to grant Sienna merit points out of nothing. Otherwise, he might get in trouble after someone else cross-checks the assignments. But granting her the merit points and letting her avoid the penalty for someone else's work was still feasible.