Splinter and Leo in “Unfinished Business”

Leonardo?

[falls over in surprise] Sorry, Sensei. Can't seem to focus.

I noticed. What is it that troubles you, my son?

I keep having the same nightmare, Sensei - every night! I let the team down. They're dragged off into darkness and I'm powerless to help.

This is not uncommon. All leaders must face the fear of losing their team. I face this every time you and your brothers' leave the lair.