Helper, n.
One who, or that which, helps, aids, assists, or relieves; as, a lay helper in a parish. Thou art the helper of the fatherless. Ps. x. 14. Compassion . . . oftentimes a helper of evils. Dr. H. More.
Shades of meaning
Fernald has no entry of its own for helper; he lists it under accessory, auxiliary.
Where he writes about it:
Colleague is used always in a good sense, associate and coadjutor generally so; ally, assistant, associate, attendant, companion, helper, either in a good or a bad sense; abetter, accessory, accomplice, confederate, almost always in a bad sense. — from accessory