Complex sentence: Her younger brother is the snobbish Roger Collins (Louis Edmonds), who has a darkly mischievous (some would say diabolical) son named David Collins (David Henesy), of whom Elizabeth is quite fond.
Split into simpler sentences: Her younger brother is the snobbish Roger Collins (Louis Edmonds). Roger has a darkly mischievous (some would say diabolical) son named David Collins (David Henesy), of whom Elizabeth is quite fond.