Scent, something that most didn't care about. Most didn't have the ability to smell someone out, nor did most care for the smell of someone. But Astartes? They're heightened abilities allowed for that. Allowed for the power to take in everything they liked about someone.

Trying to get changed out of uniform, you're met with the clingy hold of an Astartes. As he absolutely takes in how you smell. He latched himself to you and now you have to deal with this.