The Dark One child if you choose to save Pavel despite his betrayal: "He'll live...so that's what forgiveness is...thank you, I will remember this."
While going into Polis, the Dark One child is disguised as a regular boy and will wave at one of the soldiers. The soldier responses with a small salute.
While wandering the surface with the Dark One child, he'll at one point decides he wants to wear clothes like you. A minute or so later, he appears to show you his new outfit. Its the cutest thing ever.