It starts with a late night working and a spilt cup of coffee.
Funnily enough, Bart kind of asks for it. Spilling Dick Grayson's coffee at four in the morning is apparently not a great idea. Of course, Bart being Bart does exactly this. Dick doesn't even think twice when shoving him to the ground and yelling at him something or other about being a failure. A fraud. A fake.
Kid Flash agrees full heartedly. Impulse tells him to get up and hit back. His mind screams at him to move, but Bart tends to have a thing for not listening to people's rational advice, including his own. His heart ties him to the floor and he lays there and allows himself to be kicked in the ribs by Dick.
Kid Flash tells him that this is what he deserves. That Dick's suffering because of Wally's death, and since it's Bart's fault, he deserves this. Bart agrees.
Which is why he does nothing the entire time. Just allows Dick to do what he needs to do.
He hopes Wally's proud.