James and Sirius became friends early on during their time at Hogwarts. They were both sorted into Gryffindor, by which Sirius broke family tradition. The two, along with Remus Lupin and Peter Pettigrew, formed the Marauders, a mischievous group of friends. James, Sirius and Peter became unregistered Animagi after they found out Remus was a werewolf.
When Sirius was 16, he escaped from his home and went to live with James and his parents.
After their Hogwarts years, Sirius and James remained close and joined the Order of the Phoenix along with Remus, Peter and James' girlfriend Lily Evans. Sirius was the best man in James and Lily's wedding and the godfather of their son.
When James and his family were threatened due to a prophecy, Sirius was originally their Secret-Keeper to keep their location secret. However, he later gave the job to Peter Pettigrew as he thought Voldemort wouldn't expect it. This was a mistake as Peter was a spy for Voldemort and told him the location, leading to James' death. Sirius attacked Peter because of this, which lead to him getting framed for the crimes Peter committed and getting sent to Azkaban.
12 years later, Sirius escaped Azkaban and met his godson Harry, who reminded him of James. After Harry found out the truth about him, they became close until Sirius was killed in the Battle of the Department of Mysteries. Years later, Harry named his first son James Sirius Potter after James and Sirius.
Starbucks is a somewhat common ship in Marauders era fanfiction, although it is not as popular as Jily or Wolfstar. On AO3, it is the second most popular ship for James and the third most popular for Sirius.
|slash||Deamus • Drarry • Grindeldore • Rarry • Scorbus • Starbucks • Wolfstar|
|friendships||Golden Trio • Marauders|
|het||Bleur • Charry • Dramione • Drastoria • Druna • Fremione • Harmony|
Hinny • Huna • Jily • Lovander • Marthur • Nevannah • Newtina • Nuna
Red Moon • Remadora • Romione • Seekerhearts • Snamione • Snily • Tedoire
|family||Severitus • Weasley Family|
|CHARACTERS||m/f||Harry Potter • Luna Lovegood • Draco Malfoy • Hermione Granger|