This is my first attempt to write something romantic so bare with me on the mushy stuff. This is my own interpretation of Lupin and Tonks' life together so you may not agree with it all, but hey, I don't really care. Due to idiocy and convenience, the age difference between the two is not 13 years but 9 and Sirius lives with Tonks and her parents instead of James.
All Characters and Locations belong to the wondrous J.
Please review so I can get better :)

The sun had barely risen when there was a sharp knock the front door of the Tonks household. After a minute or two, the door swung open to reveal a short mouse haired girl rubbing her eyes and yawning. "What do you want?" She asked slowly surveying the early visitor. A young man with neat hair and bright eyes.
"Hello, you must be Nymphadora, I'm Remus, I'm a friend of your cousins, and he said to meet him at this time." As if by magic, a curly haired man appeared from behind the little girl grinning.
"Moony! Right on time as always"
"Sirius, glad to see you. Why was it that you needed me so urgently? Remus starred quizzically at his friend.
"No real reason, just wanted to see if you would come" Sirius beamed. It seemed as though Remus could have punched him had Nymphadora not cut in.
"Can I go back to sleep now? I have a tutor coming in a couple hours you know." She said as the tips of her hair started turning a deep shade of red.
"Alas little cousin, your tutor is already here and it would be unfair to keep him waiting for you."
Nymphadora looked up at Sirius, face like thunder and turned to Remus.
"Sorry, but you'll just have to entertain yourself whilst I get ready."
"No problem" Remus smiled a weary smile as she turned a stomped up the stairs. His first student seemed to be polite and nothing at all like her cousin, but only time would tell.
The girl thought that her new tutor seemed friendly and intelligent, nothing like his best friend, but only time would tell.

About an hour later the dishevelled looking 11 year old once again stumbled down the stairs. As she walked into her living room she saw that Remus had fallen asleep on their settee. Sirius was just about to take advantage of this opportunity when Nymphadora tripped over her own feet creating a loud crash which inevitably caused Remus to wake up with start. As his eyes adjusted to the streaks of light streaming in from the window he noticed two things. The first was his friend looming over him with a quill; the second was his student sprawled out on the floor. "Nymphadora, are you OK?" He asked whilst glaring at Sirius
"Yeah, fine. Happens all the time" She called from the ground "And call my Dora, it's easier" With that, they set to work. Remus had been asked by the Tonks to teach Dora some basics in magic before her first year. Of course she couldn't use an actual wand so Remus had prepared a sturdy looking stick for her. Throughout the day they practiced and the more familiar Dora got with her tutor, the brighter her hair became, until by mid afternoon, it was almost radiant. Also as she got more comfortable, she noticed more about him. How his eyes were older than the 20 he claimed. How behind the smile was a plethora of pain which he was trying to conceal. Mainly though, that across his face lay many scars, some old, some recent but all deep wounds. She had so many questions for him, but was too afraid to ask.

It was after night fall when Remus finally left. Before he went though, he commented on how talented she could be if her focus was just slightly higher and promised to see her in a few days.
"That Moony sure has a way with people" Sirius commented from the armchair in the corner. Dora realised that it didn't have to be Remus who answered her questions, her cousin must know at least a few of them.
"Sirius, what's wrong with him?" She asked in the most polite voice she could muster
"Why do you think there's something wrong?" He asked back
"Well, he just gives off a sad feeling even though he's smiling, his eyes seem lonely even though he was around us. The scars..." Dora was now staring at her feet, her hair and red as her cheeks.
"He's right you know, you could be a talented witch. If you didn't keep eyeing up you tutors" He said with a sly grin. Dora knew he was kidding with her but that didn't mean she couldn't retaliate.
"I'm sure you could be a great wizard as well, if you stopped ogling Potter!"
They both laughed and went to bed. Though Dora could stop wondering what had happened to the young man and why her cousin didn't want to tell her. As she gazed up at the twinkling stars that had been charmed above her head, she slowly fell asleep, dreaming of that man.