I just beat majora's mask again and realized how depressing the game is.

[FJ-Warez]

Kenology said:

wfz forgot to mention, in that scene during the ending, the Deku butler is actually there crying, mourning the loss of his son. 

In order for Link to don a transformation mask, someone has to die.  Which begs the question... who died for him to become OniLink?

 

How knows, but probably it was the spirit (Angry spirit due to the visions) of the Deku buttler's son...