I know that transactions require certain fees to ensure the correctness of the network, but i was wondering if it is possible to do the reverse operation. I want to give users that send transactions Balance.
The transaction fees are charged by the
ChargeTransactionPayment signed extension. I don't believe you could configure that thing to "charge" negative amounts. But I think you can just reimplement your own
SignedExtension, maybe potentially based on top of that, that will reward each transactor and replace/add to your signed extras (like here).