When they're kids, Horrid Henry is very sneaky and prankster but He loves Baby Lukas so much, Dennis the mermaid is calm & Jonitor Problem child is calm but they hates Baby Lukas a lot, Then Baby Lukas is very shy that he sees Horrid Henry but he's scared to come out

Horrid Henry : Woah Jonitor

Dennis the mermaid : Yeah

Jonitor Problem child : Sorry, you two!