Watari spent most of his life working at the Wammi orphanage for gifted youngsters, where he took in orphans with special gifts, such as high IQs, and raised them to fulfill their potential in later life.
A long time has passed since then, and now Watari spends his days assisting L in his detective work, and by fulfilling his needs, such as bringing him chocolate and doing errands. He also keeps things in order in L's HQ on Incognito Inside , making sure things don't get too out of hand.
Watari, pointing his gun at Adachi.