It was a few hours after Charlie had left Grimmauld Place that Sirius, in a moment of clarity prompted by the sun flooding his garden, remembered the engagement ring that James had given Lily. He had been given it his mother, who had worn it after her mother in law. Potters had worn that engagement ring for over a hundred years, and it had been crafted by some of the most respected goblins - all long since dead.
Sirius didn't know what had happened to any of Lily's jewellery, especially not the simple engagement ring that she had loved so much and had never taken off. So it was with trepidation that he approached the Lupins' cottage. For he had never thought to ask Remus what he had done with all their friends belongings. He knew some of it, he would probably know most of it, but he hadn't thought to ask about specifics like Lily's rings because ever since he had escaped from Azkaban, Lyra had been his priority, and he knew that he hadn't needed to know about the rings because there had been no cause to know.
But now Charlie was going to propose. Merlin, Sirius had never thought that he'd be old enough to have a goddaughter who had a boyfriend who was about to propose. When he had fallen in love with Lyra, when she was merely a twinkle in her mothers eye, Sirius had also never thought that he would be the one the boyfriend came to to ask for permission to marry her. Even in the furthest realms of his imagination, not once had James and Lily being dead, Lyra an orphan and left with her aunt ever been a possibility.
Sirius had always thought that it would be James that Lyra's boyfriends would ask for permission to marry her. Never him. So although the thought struck his heart and clenched it tightly, with the merest drift of memory of two of his best friends, there was also a wave of emotion, respect and relief, that Lyra had a boyfriend who respected Sirius' own position in Lyra's life enough to treat him as the father of the bride.
Bride.
Oh.
Sirius had a vision of his Lyra walking down the aisle, wearing snowy white robes, with her mothers ring adorning her finger...
His mission remembered, Sirius approached the cottage in front of him and knocked, waiting on the doorstep for either his friend or his cousin to open the door and let him in.
Cutting to the chase after greeting the couple, he turned to Remus.
"What happened to Petal's ring?"
Remus looked at him, a bemused tone colouring his voice as he answered.
"I had it placed in their vault, with everything else from their house. Why do you want to- ohh" he murmured.
Tonks looked between them, confused as Sirius nodded smugly at her husband. Her confusion was resolved when Remus next spoke.
"Charlie's going to propose?!"
"What?!" She cried, having been silent too long. "Charlie's going to propose?!"
She looked back and forth between the two men, but Remus was looking steadily at Sirius, so focusing on her cousin, Tonks cocked an eyebrow at him as she waited for him to speak.
"He asked my permission to marry her a few hours ago" Sirius explained, then added as an afterthought for Tonks' benefit "and Petal's ring was her engagement ring, Dorea had it before her, and James' grandmother had it before she did."
Remus joined the story, smiling with Sirius at the memories from long ago. "It's a tradition, I suppose it would be nice for Ly to wear her family's engagement ring. Dorea knew that her mother in law liked her when she gave her that ring, apparently she was a bit like Augusta Longbottom so Dorea was terrified when she first met her!"
"But what about the wedding rings?" Tonks asked, smiling at the stories.
"Each couple has their own." Remus responded, looking to Sirius as if to confirm his memory. Sirius nodded, a faraway look in his eye,
"Everybody's different, we'll see what Charlie and Ly decide on, but each couple - James and Lily and Dorea and Charlus and the rest of them, they always chose rings that reflected their own relationship and preferences. James and Lily had theirs engraved, James had a lily on the inside of his, and 'Wingardium Leviosa' because Charms was Lily's favourite class, and Lily had a small stag, and 'Mischief Managed' on hers, because James."
Tonks laughed, before sighing.
"They both sound so lovely, I wish I knew them both."
The faces of both men dropped, and she regretted it instantly. Remus squeezed her hand, and Sirius then divulged a story of which she had no memory - the first time she had met Ly was when she was seven years old, and Lyra was a few weeks old. Apparently the little Dora had adored the baby, and in turn, Lily had doted on her.
"You did know them" Remus murmured.
The trio sat in silence for a while, mourning the loss of dear friends together.
Eventually, Sirius took his leave, leaving behind memories that still hurt and a friend who felt as he did and longed for the days when death stepped past those you knew.
As the day waned, the man wandered into Gringotts, and formally enquired about, as godfather of Lyra Potter, the possibility of gaining access to her family vaults. Eventually, he wrangled a 'maybe' out of the goblins present and headed home. It was too late to risk going straight to Charlie's and informing him of the existence of the rings, Lyra often popped in to his flat in the evenings before heading home for dinner.
It would have to wait until tomorrow.
A/N I've decided to go with Lyra's grandparents being Dorea and Charlus, as that is the general opinion of the family tree. I added in the bit about tonks knowing Lily and James just because it seemed to fit the melancholy tone the conversation was taking.