If the person needing a guardian ad litem (GAL) is a minor child who is age 14 or over, they are the applicant and will need to fill out the paperwork asking the court to appoint a GAL on their behalf.
If the person needing a GAL is a minor child who is under the age of 14, a relative or friend of the minor, or other interested person is the applicant and will need to fill out the paperwork asking the court to appoint a GAL on behalf of the child.
If the person filing the case is incapacitated or financially incapable, a relative or friend of the minor, or other interested person is the applicant and will need to fill out the paperwork asking the court to appoint a GAL on behalf of person who is incapacitated or financially incapable.