Help with a depressed 2 year old

I'm having a bit of a problem with a two year old Ashyr, four year old Alyssa, six year old, Aidan and eight year old Andrew. Allow me to give some back information. I am the cousin of these children, my mother and their grandmother are sisters. Their mother is a drug addict, and and entirely unfit parent, so custody of the children was given to their grandmother, but the damage was already done. I'm just going to focus on the youngest one right now because he seems to need the most help, because he can't talk quite yet and can't express himself. Ashyr, is the sweetest little boy you could ever possibly imagine. He is very smart, very curious, and also a very good child. He knows right from wrong, and the most important thing, he doesn't know that anybody loves him. The reason why I am seeking help through this website is I wanted to know if the following things are abnormal behaviors for a two and a half year old child. 1. He follows his sister around constantly, and does absolutely everything she does, and well, that's not it, he follows anybody that is near him around, almost possessively, like he thinks they will abandon him. 2. He is VERY possessive over his things, Like, for instance, His great grandmother made him some shorts and got him a tank top to go with it, because she made Alyssa a dress. She handed it to me to show Ashyr and change him into it. I said "Ashyr come here look what grammy made for you!" and he came over, and pointed with an awe struck expression and then screamed "MIIIIINE" and yanked his shirt off and ran to his bedroom, calling for me to help him dress. 3. He doesn't talk at all except the following words: Mine, No, Mom, Nana, Car, shoe. 4. He always has a sort of... How do I describe it, Shell shock sort of behavior, blank face, just stands there, scared. But when the rambunctious older two are away he talks and laughs and is happy, I sort of think that has to do with him getting more 1 on 1 attention though. 5. I believe that he has a separation problem, which is only natural considering the circumstances. For instance, he was sitting next to a semi-distant family member, who wasn't talking to him or anything, he had just sat down. Then he jumped up and headed for the kitchen and Ashyr screamed and said no and I said "Ash what's the matter!" and he pointed at Pat (the person) and then cried, real tears, so I scooped him up and hugged him, and he stopped crying as soon as I even touched him. That's all that I can really think of to say at this point, at least for this one child, so please please please give me any advice, any information on whether it's normal for a child in this situation or not. Oh and the main cause of all of these problems: his mother is still allowed to live with them. The problem was that she neglects. :mad: Sorry, please give me any sort of help!