You already forgot who proposed the idea. It was an afternoon you and Sirius were both free from Order missions or any work, strolling through muggle London, just enjoying each other's company. Walked into his favorite thrift shop, looking around absent mindedly as Sirius searched for something specific on the other side. Until you saw it there.
A wedding dress—probably from a decade or two ago, sitting in its own quiet corner. There were no stains or any missing beading or tears—it looked perfect. Even for you perfectly.
That was the day Sirius and you decided to throw a middle finger to the wizarding world and get married. His family wanted Sirius to be betrothed to some cousin to continue their 'pure' bloodline. Toujours pur, as the Black Family crest said.
As the Wizarding war around you loomed, wizards and muggles lost lives every day, you two really decided on this.
The wedding was perfect. A small venue decorated with star motifs; a full bar that catered to all your friends; food that both you and Sirius took weeks on picking out.
Just you two and your closest friends. The threat of war, death eaters and family disappointment—all left outside and forgotten as the record player cycled through music.
Weeks ago Sirius grumbled about how tying a physical ribbon around each other's hands during the vow would be too cliche, but you swore his eyes glass over when you tied the silk around his wrist.
The noise of the reception slowly faded away, as the car—a black Morgan with a drop top—slowly drove away from London. Two bags packed in the trunk, wands laying at your feet as you raised your hands, catching the night breeze.
Sirius laughed with one hand on the wheel and the other one catching your hand pulling it down to his face as he pressed a kiss to the back.