I am now imagining ghost!Nea making obscene gestures at people every time Allen walks by a reflective surface.
Allen’s talking to Lenalee, he glances at a window, and Nea’s standing behind Lenalee, thrusting his pelvis and making motions like he’s slapping her ass.
Allen’s talking (arguing) with Kanda, and he glances over Kanda’s shoulder and sees Link, who’s always following him, in a mirror, standing right behind him, getting “felt up” by Nea.
Allen’s in Komui’s office, receiving the details of his next mission, and in that giant window behind Komui he sees Nea standing on Komui’s desk, acting like he’s a stripper on a catwalk.
Allen has got to be the master of all masters when it comes to holding a poker face.