For kids, yes, they're still learning, and some mistakes and hurt feelings are going to
happen in the course of learning, so I wouldn't advocate adults intervening for every little squabble (like, two kids fighting
over one communal
toy, or arguing about what to watch on TV), but if there's a steady pattern of deliberate and premeditated bullying going on, then yeah, I'd step in, whether it's physical bullying, name - calling, threats, cyberbullying, theft / extortion, repeated exclusion, or whatever.
I think that baby 2 is the one that gets the harder time, (if you'd even call it that) compared with 1, they have to wait longer at times, they cry more as they get older cos number 1 is mean to them, no matter how much you hover
over them this still
happens, I find it heartbreaking how many times I have soothed number two, crying after having a
toy taken, being pushed etc. when number 1 never experienced this harsher reality!