A tilly
A Tilly is the kind of person who will give you everything and never expect anything in return. She's generous, honest, and always thinks of others first.
Tilly: I'll help you with your math. Don't even think about giving me anything.
Tilly: I'm honest with you. I don't care if you're mad.
Tilly: I'll always be there for you. Just don't forget me.