$\text{P}$ is the brother of $\text{Q}$, who is the sister of $\text{R}$. $\text{S}$ is the brother of $\text{T}$ and $\text{T}$ is the mother of $\text{Q}$. How is $\text{S}$ related to $\text{Q}$?

Let's break down the relations step by step:
1. "$\text{P}$ is the brother of $\text{Q}$, who is the sister of $\text{R}$ " $\to$ $\text{P}$, $\text{Q}$, and $\text{R}$ are siblings. $\text{P}$ is male, $\text{Q}$ is female.
2. "$\text{T}$ is the mother of $\text{Q}$ " $\to$ Since $\text{P, Q, R}$ are siblings, $\text{T}$ is the mother of all three ($\text{P, Q, R}$).
3. "$\text{S}$ is the brother of $\text{T}$ " $\to$ $\text{S}$ is the maternal uncle (mother's brother) of $\text{P, Q,}$ and $\text{R}$.

Therefore, $\text{S}$ is the Uncle (Maternal Uncle) of $\text{Q}$.