The Australian comedian, whose latest series Angry Boys reprises identical twins Daniel and Nathan Sims from We Can Be Heroes, said that Daniel fascinates him because he is "so intense".
Lilley told The Australian: "Daniel is pretty terrifying. I didn't realise that until I saw him on screen and started to edit him; he's really quite intimidating.
"He's my favourite character in the series, so intense and so aggressive for no particular reason; everyone around him is so calm but he snaps all the time.
"He's really worried about the future and what will happen to his [partially-deaf] brother in life; he's 17, at that point in his life where he thinks about where he's going. He hasn't got to that 18 mark where he's the man, but he's heading there."
Lilley also revealed that he works "instinctively, like painting", as he believes that if you "think too much" while writing, you could "ruin everything".
He recently said that he enjoys making "provocative" entertainment and also hit back at rumours of racist slurs over new character, youth detention centre worker Ruth "Gran" Sims, saying that he is just trying to be "funny" and please his fans.
Angry Boys premieres in Australia on May 11 on ABC1.
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