For Avenger OCs
Tony and Pepper are going out for their anniversary, and you just so happened to be the only one Pepper trusts to watch Maria while they were gone. The three year old was currently wondering around the living room babbling to herself.
(If you don't know who Mari is I'm going to explain it short and sweetly; fucking Pepperony's daughter and Tony's second born. I would give more info but I'm to lazy to)
Also: If your a Tony love interest, well fuck...
I'll make you your own prompt:
Tony and the others were off on a mission so you were alone with baby Maria, you could like take her to the mall to meet Santa or just hang out. I don't know, do what you want.