unbending

crisp firm obstinate reserved

aloof distant do-or-die dug in formal hard as nails hard-line hold one's ground hold the fort hold the line incompliant inelastic inexorable inflexible intractable locked-in obdurate relentless resolute set in stone severe single-minded standing one's ground standing pat sticking to one's guns stiff strict stubborn uncompromising unflexible unrelenting unswayable unyielding uptight

flexible soft yielding

bending pliable pliant relaxed