Who pays the Realtor?

[Najla S.]

Hi!  My question is:  Is the Seller or the Buyer responsible to pay the Buyer's Realtor's fee when the Seller and Buyer agreed to the purchase without a Realtor?

Here's the scenario...My current tenant wants to purchase the SFR he's currently living in and renting from me. He approached me, without a Realtor, and said he's interested in purchasing the SFR. I said okay. Yesterday, I received a written offer to purchase from a Realtor. The Realtor has written within the offer a 1.5% fee.