I think this is such an adorable idea! I love in-game, lore-related character interactions and this would add so much depth! Plus things like that (I'm thinking Thrill of the Hunt as another good example) gives you a lore-related reason to want to really do well. So far Riot seems to have problems tying their lore into the actual game and this would be a great, and easy, way to do that. Champion-specific taunts and in-game interactions make each game feel unique, something Riot has said they really want to implement. I think a focus on interactions between the player and the champions, and between the champions, would be really nice.