Valency change

How does a language say an action was done for someone?

English hangs a beneficiary on the end of the clause with “for”, or slips it in front of the object: cook a meal for her, cook her a meal. Elsewhere the verb itself carries the news. Swahili lengthens the stem, Tagalog rebuilds the clause around the person who profits, and across East and Southeast Asia into West Africa a second verb meaning “give” follows the first. Japanese splits that second verb three ways, so one act of cooking is worded differently depending on who ends up better off — and uses the passive when the answer is nobody.