Mormont himself chose Jon to be his STEWARD.
Game of Thrones Season 5, Episode 2
Olly is my STEWARD now,
Game of Thrones Season 5, Episode 3
Grenn's a ranger. You're a STEWARD.
Game of Thrones Season 4, Episode 4
I was his STEWARD. In fact...
Game of Thrones Season 6, Episode 7
There's honor in being a STEWARD.
Game of Thrones Season 1, Episode 7