In ME2 before Tali joins the crew it's just Gabby and Kenneth down in engineering, which is weird. What if there was already Chief engineer, a Cerberus appointed one who wasn't big on the whole "aliens on the ship" thing and pushed back at Tali coming aboard when Shepard shows her the new drive core.
Cue a tirade about humanity and Cerberus values blah blah, and finally the CHENG refusing to continue working if doing so alongside an alien. Shepard nods, places a hand in Tali's shoulder and has EDI relieve the CHENG on the spot, before giving their position to Tali.
"You can pack your bags. Next time we make port you are off my ship."















