[Well, he's been here for as long as the Princess, so... probably the same time you started letting her bang you got used to her being here.]
Dude, don't let her hear you say that, the next thing you know and you'll be patrolling the desert and get done in by nightshade. [If he looks at Stiles' clothes closer, he'll also see... yep, a distinct pattern left by a near-brush with a lightning. Whoops??]