This picture I had done for a friend a good while back. He had requested this picture for his Facebook RP profile as "Frisk Dreemur," when the boy (My friend plays Frisk as a young man.) grew up with the monsters under Toriel and Asgore.

The character, the influence for the background (Waterfall), and the game that they're from are from Undertale.

Undertale - © Toby Fox