That’s also Patience. She stayed with Toriel until she found out aged boss monsters ,like Toriel, can’t grow old without having a child. So she went out of Ruins and searched for Asgore. And well, you know what happened next.
Justice’ determination overpowered Integrity’s just like how Frisk’s overpowered Flowey’s from the start of the game.
I’m surprised I’m getting fanarts when there’s no story about them, or even Frisk and Chara- But sure! They never fail to make me smile :’)