Getting Custody of the Child You Care For

My question involves adoption law for the State of: Indiana
I'm asking this for my friend. His gf has a 4 year old son, he's not the father biologically. The bio father isn't in the child's life. The mother never watches her son. He's been the primary caregiver for the child since the kid was 1 or 2. The mother has been cheating on the father with a guy who just got out of jail. She plans on moving this guy into the house with her son. The guy was in jail for drugs and he has a history or being abusive. My friend has texts from the mother saying she doesn't even want her kid. In situations like this, can he get custody of the child? He has been the primary care giver. And the mother said she didn't want the kid.

If mom consents, he should consider going through a court to get guardianship. Guardianship of a minor is described here. More information and, it would appear, some sample forms can be obtained here.