Pidge, running towards them from behind Matt:
Matt, whispering to Shiro sweetly:
Takashi, sweetie, if I turn around and see that you brought my little sister into the dangerous vastness of space and left my mom all alone without warning I will cause so much havoc and wreck so much shit it'll make Zarkon look like a saint
Honestly, if and when the gang rescues Matt I want him and Pidge to have the kind of sibling relationship where Voltron help you if you hurt one of them because the other can and will hand your ass to you on a silver platter, but get them in the right mood and they can bicker to the point where it makes Lance and Keith’s arguing sound like amicable conversations (Allura gets concerned but Shiro reassures her that this is normal).
Pidge gets far more creative with the nicknames (Matt, you really should know what happens if you attack your sister’s height one too many times), you cannot dissuade me on this.