Dating Harry would include...
-stealing his glasses
-more four eyes jokes
-hiding under his invisibility cloak together
-Harry showing you all the secret passageways
-Ron acting like he's disgusted when you two are being cute
-your pet being friends with Hedwig(imagine Hedwig being best friends with a cat)
-your parents having gone to school together
-your mom/dad having been a marauder
-Sirius recognizing you in the shrieking shack
-Remus recognizing you while he's teaching but doesn't say anything at first
-OMG, Remus telling you stories about your mom/dad
-learning to cast a patronus together
-going to the ball in fourth year together
-stealing his scarf and he doesn't know cause you're Gryffindor( or stealing it even though you're in (Y/H)