If a person depends upon you, what are you for him?

Are you his dependency, dependendee or something else? What is this type of opposite word called? I believe it is not called antonym, as that would be independent.

Solution 1:

I'd say you are his/her support or supporter.

See here and scroll down to the "noun" section.

Solution 2:

If someone depends on you and you have a legal obligation to protect, support or care for them and their interests, then you are their legal guardian. The person who depends on you is your ward or dependant.

An informal word for the person who you depend on is your rock.

1611, King James Bible, Matthew 16:18

And I say also unto thee, That thou art Peter, and upon this rock I will build my church; and the gates of hell shall not prevail against it.

1991, Robert Harling and Andrew Bergman, Soapdish, Paramount Pictures

Celeste Talbert: She is my rock, my right hand.

Solution 3:

provider

If A depends on B, then B provides for A and B is a provider.

to make arrangements for supplying means of support, money, etc. (usually followed by for): He provided for his children in his will.

to supply means of support (often followed by for): http://www.dictionary.com/browse/provide

Other words:

• supporter If A depends on B, then B supports A and B is a supporter.
• supplier If A depends on B, then B supplies A and B is a supplier.
• caregiver If A depends on B, then B cares for A and B is a caregiver.