Will it be something simple like him campaigning or will Nick see the Rachael woge? Or will he send them down blind alleys? I don't see anyone telling him about the artifact but will they tell HW if they suspect Renard or will they keep HW outside also.
I see Sean with BC not as clear cut as it seems. We see BC as the bad guys because of Billy Trump and their activities. Other then that they are wesen fighting for equal rights. What if Lucien denies association with the violent actions of BC. Shooting Dixion, that is not beyond what Sean has done him self. Especially if they paint Dixon as someone who would have been against wesen. BC then paints Eve as a rouge operative by identifying one of her targets as none BC. even if it was. Without HW information, Eve would have been perceived as going kill crazy. With Trubel gone, Meisner and Sean not seeing eye to eye. Nick will be worried about Adalind. Eve will have not one to justify to the group her actions.
Eve investigation will uncover Sean and the group is being used by BC, but who will she tell, who will believe her, they still don't trust her. I predict she will continue to protect them from BC, even though BC has them hunting her.
Near the end like in the previous seasons the truth will come to light, but a lot of damage will be done in the mean time.