Tf2 headcanon: Spy actually gets over protective/mother hen of Scout (sometimes in front of others). Also, Scout doesn't *really* like it when someone else than him insults Spy (it's his thing)
Spy is really protective of Scout all the time. For example, he’ll invisibly pull Scout out of harm’s way instead of getting a kill on a Heavy. And in the base, he’s always making sure that Scout can call back home and has everything he needs, but in a way that Scout barely notices. None of the people on their team dare lay a finger on Scout because they know Spy will come storming out of nowhere like a Hornet’s nest.
And Scout may insult Spy as often as possible, but if anyone else hurts Spy the way he does, he’ll just turn into the kind of guy you never want to mess with.