Very good question, possibly killed by humans? Kidnapped and Tortured? Studied and experimented on? The mystery adds to the allure of the game. I love the whole design of the armor that you've drawn here, I've always imagined Asgore in a more boarder or bulkier design. To me, this looks like something Asriel would've worn had he been born before the war. Really awesome, one of the best design's I've seen.