51.    Someone, somebody, something, anyone, anybody, anything, no one, nobody, nothing

A.     Compounds with some, any and no follow the above rules:

Someone wants to speak to you on the phone.

Someone/Somebody gave me a ticket for the pop concert. ~ No one/Nobody has ever given me a free ticket for anything.

Do you want anything from the chemist?

Would anyone/anybody like a drink?

Note also:

I drink anything = I don't mind what I drink.

Anyone will tell you where the house is.

B.     someone, somebody, anyone, anybody, no one, nobody can be possessive:

Someone's passport has been stolen.

Is this somebody's/anybody's seat?

I don't want to waste anyone's time.

C.    Pronouns and possessive adjectives with someone, somebody, anyone, anybody, no one, nobody, everyone, everybody

These expressions have a singular meaning and take a singular verb so personal pronouns and possessive adjectives should logically be he/she, him/her, his/her. However in colloquial English plural forms are more common:

Has anyone left their luggage on the train?

No one saw Tom go out, did they?

But with something, anything, nothing we still use it:

Something went wrong, didn't it?