Extension
It's a beautiful thing, watching Sirius and James take the Death Eaters on together.
They move around each other like they are two bodies of the same soul, like they are two extensions of the same mind.
Sirius is a hurricane, tearing through everything with the terrifying efficiency of someone who had learnt to thrive in chaos. James is clinical, taking his time, disposing off his opponents with a single well-aimed curse that he makes look so effortlessly easy.
When Sirius goes low, James goes high. Sirius flicks his fingers and James falls back, letting him tear through the enemy forces, providing protection when needed. They exchange barely a glance before they exchange roles, wands twirling to display impressive bouts of magic. Together they are order and chaos, creation and destruction, life and death.
Opposite, and yet similar enough to meld seamlessly into each other.