Ignatius Prewett was a pure-blood wizard who married Lucretia Black. He was an uncle by blood of Fabian and Gideon Prewett, as well as their sister Molly, and an uncle by marriage of Sirius and Regulus Black. Ignatius and his wife Lucretia did not have any children of their own. Given that Molly gave her third son Percy the middle name "Ignatius", presumably in honour of her uncle, it is likely that she and Ignatius were close.