• (because he never died. What’s canon? Hahahahahahaha, you all live in a very sad AU. Poor world where the Marauders are dead.)
• Sirius refuses to believe he’s aging.
  
• He’s honestly a little scared of it, because everyone else in his family got even worse the older they got. Most of the time he ignores it, because he doesn’t FEEL old. Still, he kind of looks towards his birthdays with dread and revulsion even though he knows he’s not like the rest of his family.
• It once got to the point where he invented a lie that he was five years younger than James. “Well, how did you go to Hogwarts at the same time?” “I was just too fabulous not to be let in early.”
• Even though he knows the exact number of days that he is older than James and constantly lords it over him, so no one believed the lie.
• He’s obsessed with his hair, and his hair routine in the morning takes 45 minutes. It drives Remus insane.
• Because they’re married, of course.
• They got married a little later in life than Jily, when they both felt ready enough to be with the loves of their lives forever.
• James was Sirius’ best man, and Peter was Remus’. Lily was both of their second best man, because they fought over whose best man she got to be until she threw her hands up in the air and forced them to compromise.
• Sirius has a HUGE motorcycle collection. Half of them are motorcycles that he’s never going to fix but keeps trying.
• His main excuse for it not being fixed is “his back”, but he knows his back is perfectly fine, thank you. He just isn’t good with fixing things.
• One of his favorite things to do with his grandkids is to take them places where they’ll have “experiences”. 
• He doesn’t like material gifts a lot, whether they’re given to him or he’s giving them. 
• Sometimes that means taking them to his work as an auror, because he most definitely hasn’t retired yet. Sometimes that’s a trip to an amusement park, where he goes on all the tallest, scariest rollercoasters and pretend he’s scared so his grandkids can “protect him”. He always tries to suit the experiences to their tastes, give or take a motorcycle ride or two. 
• He does this for Harry and his own children as well, although Harry is “basically our child at this point”
• Sometimes he, James, and Lily have fights over who gets Harry for the night. James and Lily nearly always win because Remus and Sirius live super close to Hogwarts since both Remus and Harry work there, so they see each other a lot more often.
• He’s the grandfather (although he prefers “Granda”) who has a pool table and neon signs in the basement. That’s mainly because Remus wouldn’t let it upstairs, but it makes it much easier for his grandkids to hang out down there.
• He has a really big backyard that isn’t maintained at ALL except for Remus’ section of it, but that just makes it all the more fun when he transforms into a dog and gives all of the kids rides on his back. 
• Sirius is also really into travelling, unlike Remus, who prefers to stay in a comfortable place in case something happens. As a result, there are a lot of weekend trips on motorcycles between the two of them. 
• Every summer, they take one big trip someplace, just the two of them. They keep it a secret between themselves, although somehow the rest of the Marauders always end up finding out and visiting.
• Remus and Sirius have a lot of dates in Hogsmeade.
• He’s surprisingly a good cook. A good chunk of Hogwarts students come into the house from time to time just for tea with Sirius because he makes the best biscuits and is willing to share.
• He defines “badass granda” 100%.
• Sirius Black lives a fulfilling life as an older man and canon doesn’t exist.

(james)