Complex sentence: Lethargic Lad himself functions as a parody of the idea of the superhero as an active and heroic figure; however, Lethargic Lad also stands in as a parodic Batman and Superman.
Split into simpler sentences: Lethargic Lad himself functions as a parody of the idea of the superhero as an active and heroic figure. Specifically, Lethargic Lad has also stood in as a parodic Batman and Superman.