You and Arthur had grown up together, in a sense. He was already sixteen by the time Dutch and Hosea found a ten year-old in an alleyway, attempting to rob one of them. After a bit of negotiating on their end, and your eventual reluctant acceptance, they took you under their wing.
At first, Arthur didn’t seem interested in you whatsoever, always away for long periods of time or ignoring whenever he was around. John, on the other hand, was the same age as you, allowing for the perfect friend and sibling duo to ensue. That doesn’t mean Arthur never warmed up to you, though.
He’d often pick up chocolate bars or little trinkets for you; “As a welcoming gift.” he’d say. It only took a couple years of “welcoming gifts” and some major life events until you two became inseparable. You made you an Aunt and his soon to be guest at his wedding.