My ds is 19 months old and this is starting already with him and other kids we play with in playgroup. But, he is somehow usually on the receiving end of it.
He is a very sensitive child and I see him getting his feelings hurt when other children are more aggresive towards him whether it is taking the toy he is playing with or physically agressive towards him.
For example, a great friends son the other day continued to pull ds' hair. Everytime he got near him, he would pull his hair and hold on!! Poor ds!! He would just run into my arms crying and a few times needed to nurse to calm down and feel better. Luckily, he didnt harbor ill feelings and continued to play. I dont blame the parents, this is normal toddler stuff, but I feel bad for him. Thankfully, they intervened and talked to their son (who is 2)when he did pull ds's hair and stayed close to them to try and prevent it. My point to this is that I think that you should always intervene when it becomes physical. If they hadnt intervened, I would have and if it didnt get better, I would have left, to protect ds. Yes, you cant protect him from everything, but I feel I should help him protect him from bodily harm. I am his mom, and he trusts me that I will keep him out of harm's way, no matter how little.
As far as grabbing toys and such, I think that you should try and let them work it out at first, but if it isnt working, then you should intervene and help. For example, ds was playing with this train at a playgroup, and an older child came over and wanted to play with it. Ds let him join, but then the other child took the child away. Ds got upset and started to cry and push to be by the train. THe other child then wouldnt let him play with it. ( The child's mom was in another room
: ) I then distracted ds with something else to play with. THe other child lost intrest in the train and ds noticed this and went to play with the train. THe other child saw this and jumped on the train to stop ds. Ds crumbles in tears. So, I very loudly( so his mom can hear whats going on) ask the other child to please share as ds was playing with it, but they can play together. No go for the other child. THis continues another time, and finally the other mom also intervenes and he leaves to play something else. So yes I did intervene, but I tried to just deal with my kid.
I know this is such a difficult thing. You dont want to be a harping mom, but you dont want your child to get picked on or have their child be the picker. I think you have to also teach your child what to do when someone takes their toy, or hits them. WHen they are of appropriate age, this is something you can play act with them. But when they are younger, I think distraction and redirecting are the appropriate interventions.
I'm not sure I helped. I will be looking to this thread for insight too.

He is a very sensitive child and I see him getting his feelings hurt when other children are more aggresive towards him whether it is taking the toy he is playing with or physically agressive towards him.
For example, a great friends son the other day continued to pull ds' hair. Everytime he got near him, he would pull his hair and hold on!! Poor ds!! He would just run into my arms crying and a few times needed to nurse to calm down and feel better. Luckily, he didnt harbor ill feelings and continued to play. I dont blame the parents, this is normal toddler stuff, but I feel bad for him. Thankfully, they intervened and talked to their son (who is 2)when he did pull ds's hair and stayed close to them to try and prevent it. My point to this is that I think that you should always intervene when it becomes physical. If they hadnt intervened, I would have and if it didnt get better, I would have left, to protect ds. Yes, you cant protect him from everything, but I feel I should help him protect him from bodily harm. I am his mom, and he trusts me that I will keep him out of harm's way, no matter how little.
As far as grabbing toys and such, I think that you should try and let them work it out at first, but if it isnt working, then you should intervene and help. For example, ds was playing with this train at a playgroup, and an older child came over and wanted to play with it. Ds let him join, but then the other child took the child away. Ds got upset and started to cry and push to be by the train. THe other child then wouldnt let him play with it. ( The child's mom was in another room

I know this is such a difficult thing. You dont want to be a harping mom, but you dont want your child to get picked on or have their child be the picker. I think you have to also teach your child what to do when someone takes their toy, or hits them. WHen they are of appropriate age, this is something you can play act with them. But when they are younger, I think distraction and redirecting are the appropriate interventions.
I'm not sure I helped. I will be looking to this thread for insight too.