Headcanon on how Dick deals with Damian's killing nature, like the fact that he did kill and would kill if his life were on the balance?
I…have actually never given this much thought. Lessee…
Dick doesn’t really give it much thought. You can’t change someone’s past. You can take the boy out of the circus, but not the circus out of the boy. The same rule might apply to Damian. You can take the boy away from the killers, but can’t take the killer out of the boy. That’s a bit disconcerting, but Dick knows he can’t let that rule his every decision concerning Damian. Especially when Damian is trying so hard to fit in with this new lifestyle.
Dick’s proud of him for that. He doesn’t say it, but let’s his actions speak for him. A hand on the shoulder when the body count is zero at the end of the night. Ruffling his hair when he snarks about how many ways he can kill Grayson in a given situation. Dick would give him hugs, but he’s pretty sure he might lose an appendage if he gets the timing wrong.
In their line of work, their lives are constantly put on the balance. Dick has turned it into a challenge for Damian to further hone his skills by telling him that it’s easy enough to kill someone to ensure you live. The real challenge is keeping them alive (and ensuring they can make a mostly full recovery) while still getting in, completing your mission, and getting back out. It’s what makes Batman the best.
Damian went a little starry-eyed at that.