Soon the plans of mr. Johnson will be set in motion *rubs hands together and snickers* 

I will have the teacher of Mike join him at the place he and Mitch are eating, planting some more seeds about evil succubi in his mind. With the chips in place, we could do the evil plans of mr. Johnson when everyone is back at the base. 

Poor Benjamin will have his trust in the agency completely crushed.

And Mike turning into a vampire can happen somewhere after that. But how do you see turned vampires? When I use vampires I usually let them have the standard weaknesses, daylight, garlic, crosses, etc.

Also, if they leave the agency, will they all split up for a bit? Or maybe after Steven tried to attack Gaia? 
Ethan will probably just go home, having enough of all the nonesense going on, he lives in the city so that is easy enough, and Benjamin might go with him. And if Mike is alone for a bit, he will be an easy victim, but they should get together after that and find a new place where they can hide and fight against the evil organisation.

Oh! and the imps need to be released. Maybe we should let Gaia and Ethan head to attic too, to find something suitable to hang in the tree, where they discover the imps. And when everything goes sour, before they leave they can release the imps.