Legion20
Well, time to see if my theory holds true: While there is no proof to support this, I theorized back during the Kandria Arc that Elina was attacked by a dying Puppeteer Abomination - causing her difficult labour and the negative emotions she experienced at the time - that itself perished upon fusing with the body of her son, killing the latter, that Lith would come to inhabit shortly afterwards. To me, it's the only logical conclusion, especially given the way Abominations tend to behave around him.