Rules:
You can only guess once per riddle (doesn't apply to five-riddle specials)
I post every day at 9:40 am PST
The first person to answer correctly will get a point to their house
Don't look up anything to help you answer
You can only score three points every week (resets Sunday)
If a house is winning by 5+ pts, the extra points they receive will be given to another house of the solver’s choice
Accepting suggestions (ask for more details)
Today's riddle:
I'm not always the most efficient with my job
But I've helped support more than one secret
My actions have also led to frustration
And I stayed behind during a certain event
Who am I?
Hint: This character is male, not completely human, and in the first half of the main series. He's not on the antagonists' side. He's younger than Harry, and has met him. He did go to Hogwarts. Although he's in more than one book, he only really appears briefly in one film in the second half.
The "certain event" was important to the plot/world and wasn't in the first half. The secrets had something to do with important characters, although different ones, and there's nothing in canon that suggests he no longer has this job
Leaderboard:
Ravenclaw: 29
Gryffindor: 24
Hufflepuff: 24
Slytherin: 22
Suggested by @Danzy2000