Who pays the fee in the smart contract?

Question

blockchain

I ask you not to throw stones right away)

With simple transfers to ethereum, everything is clear - the sender pays the commission, but when it comes to a smart contract, questions arise.

Help me to understand.

Let's say there is a smart contract that simply keeps users' money on the balance sheet and, upon request, transfers it back to their wallets.

1) Let's say the user transferred 1 ETH to the contract address, and paid a commission.
Further, the contract must record that this 1 ETH belongs to this particular user.
Do you have to pay a commission for this record? And the contract must pay for it (since he initiates the recording). But how will the contract pay a commission if its account is still 0? Will he take a commission from the balance of the user for whom he makes the record?

2) Suppose, after some time, the user decided to request this 1 ETH to his wallet. The transfer fee is paid by the sender - that is, a smart contract. The same question - where will the contract take the money to pay the commission? From the balance of the same user? It turns out that the user will receive not 1 ETH, but minus the commission?

Answer 1

1) the smart has nothing on the account, at any time everything on the wallet accounts is always
paid by the initiator