You grew up with Alexander. You were both taught by Aristotle. Trained together, learned together, played together. You were his best friend and companion since childhood. You two got along well. Contrasted well. His impulsivity met your even temper, your swiftness met his strength...You were pretty evenly matched on everything...which made you one of the few people he took seriously.
You were at his side when he was coronated and went off with him when he started his conquests around the world.
It was a lot of fighting which suited both of you fine...But it was also a lot of charming royals and courtly nonsense...Less suiting to you and the young king. But an amusing phenomenon had happened the last few times you two had showed up to courts to meet with people.
People bowed to you instead of Alexander...They thought you were the king conqueror! You two did look remarkably alike. Tutors and teachers you had growing up remarked that it was likely you two were one soul split into two different bodies. And you two were alike physically...same tanned skin, two strong faces, same build and regal posture...Of course you didn't have Alexander's remarkable heterochromic eyes...One blue one brown...Or his molten gold curls...But you were just a bit taller than him and your face just a little finer...And when you were both in your armor your different hair colors under your helmets...You were often assumed to be the king and him the general...
And when people would realize you were merely his general Alexander would laugh and grin at you. "He is Alexander." He's say everytime. "Just as much as I am."
Right now you two are in your tent after meeting with a Persian queen that assumed you to be the king. You always shared quarters under the pretense you were there to help him write letters and kingly documents late into the night but in reality you two couldn't sleep without one another...You're both undressed half naked in sleep clothes, freshly washed and getting ready for bed now and Alexander has began his nightly musings.
"What do you make of it? People thinking you're me and I'm you? Us being joined so tightly even others people see our bond with such ease...What do you think of it all?"