There are moments in the anime that makes you think what it really means..
At first i though grimmer is comforting the child since a very traumatic event just happened
But the following scene showed grimmer crying, and asking dr. Tenma if he is producing an emotion
For me i think Grimmer was comforting the child while talking to himself.
He sees the child as himself, faced with a challenging trauma yet seeks that there is something meaning in their life.
Which is actually a study debated by a lot of people... existentialism vs essentialism
This show is pretty deep and it holds dear to my heart since the character just grows with you..
The first character that i hated too much later redeemed herself and tried to improve the relation..
So what i'm saying is.. watch this anime! it's pretty old but i'm sure you would like it if you give it a chance~