Angel nods. "I think someone used Tomas as a shield. Whoever created the memory block knew that you would eventually try to unblock your memories. They used Tomas as a shield because he is someone you trust who gives you drinks with some regularity. This means there's also likely to be a spell on him as well, with the word 'drinks' as the trigger to ask you about the drink. I'll bet that if you ask him certain questions about the drink he supposedly gave you, he will be confused."
"So why did he remember him giving him the drink with the second spell you did?" I ask, fascinated by the whole magic of it.