Question on VAT supply of services

Company A has a service agreement contract with company B. A provides professional services to B. I understand VAT normally follows the party contractually supplied with the services. Let’s say that standard VAT applies between these two companies. However, if company C (who avails of 0% VAT on acquired goods and service) settles the fee invoices on behalf of B, how does VAT operate then? I guess my question is whether VAT typically arises at the point of sale between B2B/B2C or follows the service agreement contract. In which case, VAT-able fee invoices must be supplied to either company B or C depending on who foots the bill. All companies are incorporated within the same country for reference.