When rats get into an argument, they will stand up and remain at arm's length while they decide whether it is worth fighting about. This short clip shows two rats standing off, but they do not escalate to a fight.
This video shows a baby rat grooming his mother. Rats often groom other rats as a sign of affection, and often as a sign of dominance (usually called power-grooming).
Common behaviour among rats is not wanting to share food. This rat has a small treat, and this video shows how every other rat in the cage is trying to steal it from him. Note how when another rat approaches his face, he will pivot quickly, turning the opposite direction to prevent the other rat from stealing his prize.
This pregnant rat is in the process of rearranging her nest. Mother rats will usually make and remake their nests a few times before they give birth, wanting to make it perfect for their babies.
This video shows the classic dominance behaviour called 'power-grooming', where a rat asserts his dominance by grooming another rat fervently, pushing him down so his belly is exposed but not hurting him. This can also be seen as a play behaviour.
