This takes place in an AU timeline, in which Remus survives the final battle and Tonks does not.
The knock at the front door came in the same moment that the baby started crying. Remus headed straight for the nursery; whoever was outside could wait, or leave for all he cared. He had only just picked up Teddy, the crying ceasing immediately, when his mother-in-law appeared in the doorway.
"Remus? Minerva McGonagall is here to see you." She stepped into the room, already reaching for the baby.
Remus shook his head. "I'll take him down with me." He was reluctant to let go of the warm body clinging to him, the small head laying on his shoulder, one hand resting on his neck.
He found McGonagall in the study, reading the spines of books. "Minerva," he said softly.
"Remus." She turned, her lips quirking up a little into a smile when she saw that he was not alone. "And this must be Teddy."
Teddy's response was to drool a little from the corner of his mouth and turn his hair the same dark green colour as McGonagall's robes.
"How extraordinary. May I?" Her outstretched arms surprised him, but not as much as the easy way that she held the baby. It spoke on natural instinct or more experience than he had assumed she had. Still, he couldn't help but move a little closer, just in case.
"I've come to offer you a job," she said after a moment's silence, her voice soft but firm.
"You are very kind, Minerva, but..."
"I'm not being kind. In fact I'm rather hoping that you will be the kind one. The children need you. After last year especially, they need you."
"I'm the last sort of person they need. They need dependability, someone who can be there fer them 100%. Even under better circumstances I couldn't offer that."
"Pish and tosh." Teddy laughed at the new words, reaching for McGonagall's mouth. The older woman smiled down at him before looking back at Lupin, eyes slightly narrowed. "You really are a ridiculous man sometimes, Remus. They need someone they can trust, they need someone who has their best interests at heart, and they need someone who will teach them to defend themselves against the dark, not worship it. You are the best Dark Arts teacher we've had in years."
"Most of your DA professors in recent years have been death eaters, Minerva. That's not saying much." He didn't allow himself to seriously consider her offer. All the reasons he had given Dumbledore for his resignation four years ago still stood, and now there were hundreds of more reasons, his son being at the top of the list. Teddy came first, always. He had promised his son on the day of his birth that he would be there for him no matter what; he had made the same vow six weeks ago at his wife's grave.
"Hermione Granger is coming back."
The segue was so very Dumbledore-like that it took Remus a moment to comprehend what she meant. "As a student?"
Minerva nodded. "She sent me an owl last week, asking if she might come. You know Miss Granger; never satisfied at giving something less than her all. She wants to attend her seventh year and take her N.E.W.T.s in the spring; she's not content with simply passing seventh level W.O.M.B.A.T.s."
"It will be hard for her, not to have Harry and Ron." His hand curled into a fist, seeking the fingers that weren't there anymore to entwine with his. Hermione, at least, would have her friends at holidays.
"It's time for all of us to begin rebuilding." With great care she gave him back his son. Before leaving the study she paused at the doorway. "I'll wait a week before looking for another professor. You know how to reach me."
And then she was gone, and once again Remus was alone.
xxxxx
He didn't say anything to Andromeda about McGonagall's offer, and she didn't ask. She was one of the reasons he had said no; after losing her husband and daughter in the space of a year he didn't feel right taking her only remaining family out of the country. They had never discussed living arrangements; he had simply come here after the final battle because it was where Teddy was, and stayed. Remus had wondered more than once if she was afraid to bring up the subject, worried that he might voice his intention to leave. It was laughable, really; he rarely ventured farther then the back garden these days. When he did leave it was to visit Tonks.
"I'll be back in an hour," he told Andromeda two days later, a few minutes after he put Teddy down for a nap.
"I'll be home all afternoon; why don't you stay out for a while, visit Harry or stop by the Burrows?"
She made the same suggestion every week, and every time he shook his head. An hour was as long as he allowed himself with Tonks, because he sometimes felt he could stay there forever and knew it would do no one any good if he did. It was also as long as he could bear to have Teddy out of his sight. "I'll be back in an hour. Teddy should sleep the whole time, but if he doesn't..."
"I know what to do, Remus. I did survive Nymphadora's infancy, after all."
Survive. Something they both had done and Tonks had not. The word hung in the air between them for a moment before he turned and left.
Her grave read 'Nymphadora Tonks Lupin' with dates only a little more than 25 years apart. The days after her death were little more than a blur so he had no memory of discussing what it was to say. Sometimes he was tempted to change the writing, knowing how his wife had disliked her full first name. He left it for Andromeda's sake, and some perverse hope that she would take to haunting him if she learned of it.
"You're brooding again, Remus."
"No, I'm not." With his finger he traced each letter carved into the stone, starting with the 'd.'
"Your eyebrows are furrowed, you're fiddling with a loose thread on your cardigan and you've been staring at the same piece of grass for close to ten minutes now. If that's not a good brood I don't know what is." It was the sort of conversation they'd had a hundred times before. "Are you thinking about Professor McGonagall's offer?"
"She's Headmistress McGonagall now. I suppose that means there will be a new transfiguration teacher at Hogwarts this year." It was strange to think of; even his parents had had McGonagall for transfiguration.
"I'm sure there will be, but you're changing the subject. Why didn't you tell her yes already?"
"You know why."
"I know that you're meant to be a teacher. The first time I heard you laugh, really let go an laugh, was when you told Sirius the story about Neville's boggart. You were so proud of him, just as you were proud of Harry's Patronus and Hermione's cleverness and all the other students you told me about."
"Maybe if things were different."
"Things are what they are, and all you can do is make the best of them."
"Teddy..."
"Teddy will love Hogwarts as much as we both did. You told me once that your time there was the best years of your life."
He shook his head. "My time with you was."
"There you go with the flattery again. You'll make me blush, Remus John." He heard her laugh, a sound with more magic to it than any wand could hold.
"Dora." He closed his eyes and could almost imagine the touch of her hand on his cheek.
"You can't go on like this anymore. It's not good for you or Teddy or mum. I know you needed time, but now you need to begin living again."
"You made that impossible to do without you."
"You have me, Remus. In your memories, your heart and most of all in our son. Live for him, if you can't figure out how to do it for yourself yet." The voice was growing fainter, as it had been for some time.
"Not yet. Please, I..."
"Go home, Professor. Kiss Teddy and write your letter to McGonagall. It's the right thing, and if there's one thing I've known about you from the start it's that you always do the right thing."
"Tonks." He opened his eyes, but knew without looking that he was alone. Sometimes his memories were so sharp that thought he half believed she was really there, talking with him.
"I love you." Without another look he apparted to the house, arriving next to the crib where Teddy still slept. He spent some time simply watching before going downstairs to start a letter.