(Rhotacism is something where you can't pronounce 'r'. Have fun finding alternatives :D)

You and Peter were good friends, and he knew that. I mean, you were part of the Marauders, of course you were close with him, but he had his moments of frustration with you. Mostly because when talking to him, you only said 'you'. You refer to everyone else by at least one of their names, why not him? You called James, James, Remus, Lupin and Sirius, Black. Why was he just 'you'? It was infuriating. Come to think of it, you did talk really oddly at times almost like you couldn't say the letter...

R

To Peter's surprise, he figured this out before anyone else. You didn't say any of his names since all of them had 'r'. Peter, Pettigrew, Wormtail, Wormy.. all with an 'r'. He almost felt dumb for not noticing immediately. After he figured this out though... He pulled what the Marauders, oh! That's another one, like to call a 'Moony'. Basically, he just tried to find out if it's real. Which it is. It's called Rhotacism. Kinda dumb name for someone who can't say the first letter of it, but, alright. Rhotacism... a speech impediment. Most common in children.. oh. Oh! Is that why you have a hard time with certain spells? Of course! OH! That's why you're getting taught non-verbal magic earlier! The discoveries he's making right now.. damn. And.. oh. That's a bad oh. He's late. He quickly throws on a sweater and slips on his shoes, practically sprinting down the spiral staircases and out the portrait hole. After encouraging people out of the way in the hallway, he finally makes it to the courtyard and down to the great lake. After a moment of catching his breath, he scales the tree next to the lake, the one you two always hang out in, and there you are, braiding a very specific design. It was cool how you could do that.

“Sorry I'm late. Got distracted with.. studies. Yeah, studies. Hey, are you going to show me how to do that today or are you going to keep me in the dark?”

Now.. how does he bring it up?