Even though Rowie desired to tell Vanilla that he had the opportunity to meet his mom ever since he had been presented with the idea, inside of him he knew well something that he didn't know; how would Vanilla exactly react to the news. Would she become amazed? or perhaps one of her rushes of curiosity would spark on her?
It was a possibility, but her mother and her death were a sensitive topic for her, even if she barely talked about it. He could just end up disturbing her or end up opening ancient wounds inside her, for putting it in the same words of her mom. If telling her about her mom ended up being a bad choice, he could end up causing her pain. Vanilla was already too tangled up mentally and disturbed enough between her uncertain destiny and the trouble she was in to only get more disturbance.
"...I promise," He responded. "Vanilla won't know about this."