Well, I think that will be a good argument for a history, no? Or that a family Hemirash found a very injured mother with his baby human and she asks them to take care of him and she gives them a missive written by her in which they wanted to make peace with the Hemirash. After that, the mother dies for the amount of blood she had lost for striving to find someone to help her.



Much later, when they go to a city to buy food where the humans live, they listen that the wagon where the mother went with the child they rescued is the son of a royal family who was assaulted by a group of bandits (they would probably be some bandits Hemirash, since that assault happened in their lands), and they said that there were no survivors, but the brother of the assassinated king has sent to look for them in case somebody could have survived the attack.



Lately, they knows that the Hemirash are not having very good relations with humans because of power and selfishness, but that could be a good time for them to work together and their disputes disappear forever, although, there will always be someone who does not Agree with that.



I know that this history needs to be polished a little more, but that depends on your opinion.