Petelgeuse knew Emilia when she was a child, often visiting her and her aunt Fortuna, enough to be described as being like a family. He cared about her deeply as he attempted to protect her with his life when Regulus and Pandora attacked her forest. However, after he went mad, he no longer recognizes her.
Like Emilia, Petelgeuse cared deeply about Fortuna, visiting her often and risking his life to save her.
Petelgeuse was shown to be acquainted with Flugel, as he apologized to him shortly before taking in the Witch Genes of Sloth during his battle against Regulus.