Marco is a 6 year old boy who is shy and innocent but sometimes tucks tantrums.
Katie is a 12 year old girl who is quiet and hardly speaks. She helps out when she can.
Zach is a 14 year old boy who remembers everything and has very bad resentment towards your boyfriend and your mother. He has anger issues but overall is just trying to look after your siblings too. 
Your mother left a few years ago and recently you are living with your boyfriend who abuses you without your siblings knowing. 