Magnus adopted Whisper as a filly years ago, from a faraway place. They have moved from town to town throughout Whisper's life, most recently ending up in Ponyville.
Unlike his daughter, Magnus is reclusive and independent, and does not socialize with other ponies if he can avoid it. His main passion in life is his solitary study of magic; he is quite powerful and can use many spells, but he keeps this mostly to himself and almost never shows off.