
Rotties as pups are very inquisitive they need to be around people so if you are exited around your grandson which is normal hes going to feel the same...(mummy loves seeing him id best greet him the same)hecan only learn from you and your actions so if I were you id keep him behind a gate whilst your grandson comes in and for a good hour to let him calm himself...then bring your puppy out on a lead a short one and get him sitting and sit your grandson on your lap...(puppy on the floor) he needs to know your grandson is a higher ranking than he is right from the start...rotties are smart he'll learn this quick but at the same time you don't want resentment so id make sure its a 5 minute meeting maybe even just 3...don't use a squueky voice use a calm voice and say good boy when you get the good behaviour...
its always best to(with any breed might I add)supervise children with dogs and puppies,for the safety of both...
your pup is just exited to see a play mate that's all but you don't want him knocking him over by mistake and getting to his teen stage and trying his luck with your grandson you want that to be with you!!! so u can set him damn well staright
good luck im sure youll be fine x