when he was young his mom owned a painting and the muse was the man she loved. his dad (her husband) thought she had an affair with that man which is why ash has one eye her color and one eye the other man's color (anyway its not the husband's i think his eyes are brown. He didn't like that she hung that painting cuz it made him jealous. To her the painting just represents a feeling and that he was the one she loved now (although i still suspect that ash is the other man's child so iunno). anyway ash understood the concept of love through his mom and that painting and wanted to be like her, to treat the person he loves like she does, kindly and with a smile (he was probably too young to understand cheating). One day they went to buy art supplies and ran into that man, there was a terrorist attack and some unknown events happened. The man (who he doesn't understand is his possibly dad, come on we know it is) protects ash because he is the son of the woman he loves, while the mom protects them both because she loved them both. He sees that as the ultimate act of love, which is sacrifice. Anyway she died and her widowed husband abandoned him (not sure about his sister, seems she's the one that provided for him while maybe that dad provided for her). Ash wants, desperately, to find that painting because it belonged to his mom and it was the motif for love in his life. The husband sold it after she died and he didn't know where it had been sold to because he could never find it (it was bought by his mom's old lover is most of our guess). And that's about it.