[It is Rin's own assumptions about Meridian Men (soft hearted, sentimental) and Advocates (subdued, pushovers) that make it so she feels confident leaving him alone in there. If he is so much like Gray, then there is no issue with him.

As it is, it didn't really matter if he did well. It was simply something to keep him busy while she was out. When she comes to find him... unmoved, she's a little unsettled. However that is outweighed by the fact he is looming statue in her own shop. For a moment it almost feels like he belongs there.]

Already finished? Perhaps I should have given you something more difficult to do.

[Tohsaka puts the brush down on the table — the wooden paddle facing upward, and the bristles on the tabletop. Once she's behind the counter, set across from him, she reaches under to procure an emerald green gem. It looks small, like something that would be inlayed on a vase or something similar.]

There might be a burning wood smell shortly.

[After pressing the gem to the back of the brush, its tip begins to scorch a pattern onto it. Rin encourages the magical energy she had stored in the gem to flow outward and inscribe a magic circle onto the brush. When the circle is complete the gem shatters. Almost into nothingness.

An expensive hobby, to be sure.]

Pour the mixture into the scorched depression.