i think as for the interchangablilty, its also interchangably literal and metaphorical
lyrics i think fit flint specifically are
IM GONNA WIN, IM GONNA TRY,
ILL NEVER LOSE, ILL NEVER DIE
YOU'VE SEEN ME BEFORE, YOU'LL SEE ME AGAIN
I NEVER GIVE UP, I'LL NEVER GIVE IN
TILL IM BLOODY AND BRUISED
TILL IVE BROKEN MY BONES
TILL I WONT BE ABUSED
TILL IM LAUGHING ALONE
flint is extremely determined and will literally fight until near death (as shown with Thea, among other things) but i think this line is also interchangable for slav
i also think ITS HARD TO BE CHARMING AND SMART AND DISARMING ITS HARD TO KEEP UP WITH THE REST/PRETEND YOUR THE BEST
fits (edited)