steadfast

abiding allegiant ardent bound and determined constant dependable determined devoted diligent dogged faithful fast faster fastest firm fixed fixed gritty hard-core hard-line hell-bent immobile immovable immutable implicit inalterable incompliant indefatigable inferred inflexible intent liege loyal more constant more diligent more loyal more solid more permanent more whole hearted more trustworthy more trustworthy more wholehearted more wholehearted more whole-hearted most loyal most whole hearted most wholehearted most wholehearted motionless most trustworthy most trustworthy most whole-hearted mulish obstinate permanent persevering persistent purposeful resolute responsible reliable religious secure set single-minded solid stable staunchest staunch steady-going steady steady stock-still strong stubborn sturdy sure surest tenacious tireless tried true-blue true trustworthy/trusty trustier trustiest trustworthy unbendable uncompliant uncompromising undaunted undoubting undoubting unfailing unflinching unflinching unhesitating unmovable unmoved unquestioning unqualified unwearied unswerving unuttered unwavering valiant weariless wholehearted/whole-hearted wholehearted