Earnshaw sat, morose as usual, at the chimney corner, and my little mistress was beguiling an idle hour with drawing pictures on the window-panes, varying her amusement by smothered bursts of songs, and whispered ejaculations, and quick glances of annoyance and impatience in the direction of her cousin, who steadfastly smoked, and looked into the grate.
There are no more uses of "steadfast" in the book.
Show samples from other sources
But then, that’s who Helene is: Her faith is steadfast.
Sabaa Tahir -- An Ember in the Ashes
Moving apace with the river was a long single-file line of men, eyes aimed at their feet, shoulders tense, walking steadfastly nowhere.