If you have not seen "Dark Water," this is not for you. Trust me, move along. There are MAJOR spoilers in this. :)
Mistress of Disguise
There he was.
After months and months of awaiting his arrival, he stood directly in front of her. The Doctor. The man who simply left her for dead at the hands of the Time Lords, too worried about his dear, precious humans to spare even a penny for her thoughts. Pah, no matter. It wasn't as if she'd made an attempt to save his life only moments before her abandonment.
Oh, but she did? And he still abandoned her?
How very, very... naughty.
He should suffer for what he's done. He... should... squirm.
Missy marched right up to him, shot daggers into his calm, calculating blue eyes, (so different from his last incarnation), and then kissed the hell out of him. To her absolute glee, he reacted less than enthusiastically. He tried to push her away, but to no avail. No, she couldn't let him get away that easily. Just to torture him even more, she forced her tongue through his lips.
When she pulled away, the Doctor looked mortified... confused... assaulted.
Wonderful. Just like she wanted.
Missy kissed his silly looking nose for good measure, and then waltzed away, wholly satisfied.
She couldn't wait to see his reaction when he finally realized who she was. After all, every Doctor needed a Mistress...