Just saw this thread....
The broken ribs and glasses are unacceptable. If this happened to one of my kids law enforcement would be involved. That is a serious assault and should be handled as such. What the school does is secondary. Snitching is not an issue since the kid had broken ribs so YOU take the issue forward.
With today's PC, one has to be careful with how one handles a bully. Both of my kids have had problems but nothing serious like broken ribs. Our oldest has had the worst problem at a school she used to go to. There was a bully who was a couple years older than the other kids. My impression was that he was learning from his father. We made the school and teachers aware of the problem which they already knew about. When I would pick our up our child they would often be outside playing. I noticed behaviors that the teachers were simply missing.
Since there is a limit to what the school can do and they cannot see everything, I taught our child to hit. Hit HARD.

I showed her how to make a fist and HIT HARD without hurting herself. I then let her hit my stomach.

I have a strong stomach so I let her flail away. :laughing: Did I mention I taught her to HIT HARD.
We also talked that if she did fight back I would have to deal with the school. That was ok because if the bully was hurting her it needed to stop. Since the school had been notified by multiple times by multiple parents, if the problem continued it had to be solved by my kid. She needed to know that there would be more than the physical fight with the bully and not worry about. That was my problem.
One of my kids friends was a smaller boy. They both were having problems with the bully who was much bigger than them. The bully really had issues. He challenged ME one day. He ran at me as fast as he could to see if I would jump out of the way. I did not. He was surprised.
One day after school I arrived just as the kids were going back into the building after being outside playing. My daughter and her friend were almost the last kids going into the building. They were out of breath, running, but laughing. I knew something was up. As they entered the building the bully turned the corner and he was in a world of hurt. :thumbsup::laughing: He was dirty and covered with grass and straw. He was holding his stomach and was in a bit of pain.
On the drive home I found out what happened. Or at least some of it. My daughter as playing with her friend on the monkey bars. The bully went after her friend. Somehow the bully got hit or kicked in the stomach. :laughing:
No more problems.
Course your grandson has to realize this and do something. On the other hand he might not have a problem with one kid but a group of kids. That would not be something he can handle by himself.
Him being a loner can be a problem but then so can being the a popular kid. I grew up mostly with adults. I did have friends but not alot of them since I went to quite a few schools in different states so there simply was not time to have a bunch of friends. I went to three high schools as an example. Two of the high schools were in the same city since I was bussed but you made friends one year and they were gone the next. I got along better with adults and younger kids than kids my own age.
It sounds like he needs confidence building. If he was interested in martial arts and there was a good school nearby that would be a good option.
I really do think you need to dig deep into the bullying. He is very likely NOT telling you everything that is happening. My parents did NOT know how one of my teachers behaved in one grade. They were shocked when I told them over the last year or two. The teachers was a nut job but they had no clue. His ribs getting broken is serious.
Raising kids sure ain't easy.
Later,
Dan