Final answer:
There is not enough information in the provided excerpts to determine which uncle fled to Russia and was in a miserable marriage. The excerpts discuss individuals escaping slavery and their family connections, but not the specific details required to answer the question.
Step-by-step explanation:
The uncle who fled to Russia and was in a miserable marriage is not explicitly described in the excerpts provided. These excerpts mention various individuals and their relationships within the context of slavery, escape to freedom, and family units, but none of these individuals are mentioned as having fled to Russia or being in a miserable marriage. Therefore, there are insufficient details in the references provided to accurately answer the student's question regarding John, Michael, David, or Robert.