In truth, Ed had suspected it was something as simple as a kiss. He's spent time handling John's volatile self, Joker's overt sexuality, Vrenille's teasing, and the frankly brutally sexual relationship between Riddler and Cinder (and maybe Harley now?).

If Oswald had said he wanted Ed to strip here and lay down bare for him, he would've seriously considered it. But a kiss is more than he's willing to share, give, let Oswald take.

It lingers. He dips into it carefully, suckles very briefly and gently on Oswald's lower lip and then slides the tip of his tongue over it again.