This is a little 3rd Generation Headcannon that I wrote a lot ago, but my Marauders are in it too. (I just love them so much, I can't leave them... :P). It's my first try to write in English (it's not my first language), so please don't judge too hard, ok? ;)
Hope you like it!
Adrienne Lupin
James and Padfoot
Harry never got over Sirius' death. When his kids were born they started to ask for a pet dog. Harry at first didn't want because he knew it would remind him of Sirius, but after many years of them asking it, he gave in.
The family one day went to a pet shop to look at some dogs. When they were there they started to look at them. James was walking alone, only glancing at the dogs in the cages... when suddenly stopped. There in a cage at the end of the shop was the most beautiful and black dog James had ever seen. They looked each other for a moment, and for some unknown reason, he fell in love with it, he only wanted it.
James ran back to his mother and father and went with them to the dog. Ginny saw the tears in Harry's eyes and asked James to look at some other ones, but Harry looked at the dog and just smiled, while the tears were rolling down his cheeks, and agreed.
Half an hour later the potter family was at Grimmauld Place with the new dog, which Harry named it Padfoot. Soon, everyone loved it, but the person Paddy was closest, was James: they were always together. Wherever James was, the dog was. Whenever James was up to no good, whenever James was going to prank somebody, Padfoot was by his side. Every time Harry looked at them, he smiled, and imagined the Marauders.