How to Unlock Mercenaries
You’ll unlock Mercenaries as you progress through the game and Diablo 4 Items complete various quests. Your first Mercenary, Raheir, will be unlocked after completing the main quest, The Hand Remembers the Blade (Act VII).

Rather: Unlocked by completing the quest The Hand Remembers the Blade.
Varyana: Unlocked by completing Slayer's Retribution.
Aldkin: Unlocked by completing A Nameless Mystery.
Subo: Unlocked by completing A Feather on the Scale.
When you unlock a Mercenary, you also unlock a new personal hub area known as The Den. The Den serves as the base of Diablo 4 Items for sale operations for managing your Mercenaries, and it’s where you’ll recruit and interact with them.