I absolutely adore how well the themes from the games play into these doujins. Lillie having to rely on the player for protection while at the same time wanting to be able to protect herself and be independent while not losing their friendship is such a wonderful thing. It definitely helps that Lillie is pretty clingy in game. If you pick a female character and have a good pair of yuri goggles on hand, it's a pretty wonderful experience, and it's only natural for it to be expanded on in this way.